Brownies & BarsAmericanEasy

Slow Cooker Stout Beer Chocolate Chunk Bars

Name: Slow Cooker Stout Beer Chocolate Chunk Bars
Prep time: 15 min
Cook time: 3 h
Total time: 3 h 15 min
Yield: 16 servings
Cuisine: American
Ingredients: ¾ cup (180 ml) stout beer (such as Guinness or a local dark stout), room temperature, room temperature, any sediment settled; 6 oz (170 g) dark chocolate chunks or roughly chopped dark chocolate (60–70% cacao); ½ cup (113 g) unsalted butter, at room temperature; ¾ cup (150 g) granulated sugar; ½ cup (100 g) packed light brown sugar; 3 large eggs, at room temperature, at room temperature; 1½ tsp (7 ml) pure vanilla extract; 1 cup (120 g) all-purpose flour; ½ cup (50 g) unsweetened cocoa powder, sifted to remove lumps; 1 tsp (3 g) instant espresso powder; ½ tsp (2½ g) baking powder; ½ tsp (3 g) kosher salt

From the MyKitchenBank Kitchen

Rich, fudgy chocolate bars infused with the deep, roasted notes of stout beer, cooked low and slow in a slow cooker for an impossibly moist, dense crumb. Dark chocolate chunks and cocoa powder create layers of chocolate flavor, while a hint of espresso powder amplifies the beer's complexity. These bars have a brownie-like texture with a slightly sticky top.

Prep: 15 min
Cook: 3 hr
Wait: 30 min
Total: 3 hr 45 min
Makes: 16 bars (8×8-inch square)

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Ingredients

16 servings

¾ cup (180 ml) stout beer (such as Guinness or a local dark stout), room temperature, room temperature, any sediment settled
6 oz (170 g) dark chocolate chunks or roughly chopped dark chocolate (60–70% cacao)
½ cup (113 g) unsalted butter, at room temperature
¾ cup (150 g) granulated sugar
½ cup (100 g) packed light brown sugar
3 large eggs, at room temperature, at room temperature
1½ tsp (7 ml) pure vanilla extract
1 cup (120 g) all-purpose flour
½ cup (50 g) unsweetened cocoa powder, sifted to remove lumps
1 tsp (3 g) instant espresso powder
½ tsp (2.5 g) baking powder
½ tsp (3 g) kosher salt

Equipment (8)

6-quart or larger slow cooker
Parchment paper
8×8-inch (20×20 cm) square baking pan or slow cooker liner
Medium mixing bowl
Large mixing bowl
Whisk
Rubber spatula
Instant-read thermometer (optional but helpful)

Steps

Before you start

Line your slow cooker insert with parchment paper, extending 2 inches up the sides for easy removal
Have all dry ingredients measured and combined before starting
Use a slow cooker on low heat—high heat will cause the edges to cook too quickly and dry out
Allow bars to cool completely in the slow cooker before cutting for clean edges

1
Prepare the slow cooker
- Line the inside of your slow cooker insert with parchment paper, pressing it into the corners and allowing 2 inches to extend up the sides.
- This prevents sticking and makes removal much easier.
- If you have a silicone slow cooker liner, you can use that instead.
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Tip: Parchment paper is essential for easy removal of these delicate, moist bars.
2
Combine dry ingredients
- In a medium bowl, whisk together the all-purpose flour, sifted cocoa powder, espresso powder, baking powder, and kosher salt.
- Set aside.
- This prevents lumps and ensures even distribution of the cocoa and leavening.
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Ready when: Mixture is uniform in color and texture, with no visible cocoa streaks
Tip: Sift the cocoa powder beforehand to remove lumps that won't incorporate during slow cooking.
3
Cream butter and sugars
- In a large bowl, beat the room-temperature unsalted butter with the granulated sugar and brown sugar using an electric mixer on medium speed for 2–3 minutes.
- The mixture should look pale, fluffy, and noticeably lighter in color.
- This incorporates air and helps create a tender crumb despite slow cooking.
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Ready when: Mixture is pale, fluffy, and increased in volume by roughly half
Tip: Cold butter won't incorporate properly—make sure it's truly softened to room temperature.
4
Add eggs and stout
- Add the 3 room-temperature eggs one at a time, beating on medium speed for about 30 seconds after each addition.
- Once all eggs are incorporated, slowly pour in the ¾ cup of stout beer while beating on medium speed.
- The batter will look slightly broken and loose—this is normal.
- The beer adds richness and a slight bitterness that complements the chocolate.
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Ready when: Beer is fully incorporated; batter looks emulsified though slightly loose
Tip: Room-temperature eggs emulsify better and prevent curdling. The mixture may look curdled—it will come together when you add the dry ingredients.
5
Add vanilla and fold in dry mix
- Stir in the 1.5 teaspoons of vanilla extract.
- Using a rubber spatula, gently fold the reserved dry mixture into the wet batter in two additions, stirring just until combined.
- Do not overmix—fold until you see no white streaks of flour, then stop.
- Overmixing develops gluten and creates tough bars.
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Ready when: Dry ingredients are no longer visible; batter is smooth and uniform
Tip: Gentle folding prevents overdevelopment of gluten, which would toughen the bars during slow cooking.
6
Fold in chocolate chunks
- Fold the 6 ounces of dark chocolate chunks into the batter with a few gentle strokes of the spatula.
- Some chunks will break into smaller pieces as you fold, which is fine—you want a mix of chunk sizes throughout.
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Ready when: Chocolate chunks are distributed throughout the batter
Tip: Don't overmix or you'll break the chocolate into tiny pieces; you want visible chunks.
7
Transfer batter to slow cooker
- Pour the batter into the lined slow cooker, smoothing the top with a spatula to an even thickness.
- The batter should fill the slow cooker insert to about 1½ inches depth.
- Place the slow cooker insert into the slow cooker base and cover with the lid.
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Ready when: Batter is level and fills the insert to about 1½ inches
Tip: Make sure the insert sits flat and is fully seated in the slow cooker base for even cooking.
8
Cook on low heatOven 200°F / 95°C
- Place the lid on the slow cooker and set it to LOW heat.
- Cook for 2½ to 3 hours, checking at the 2-hour mark.
- The bars will rise and the edges will set first, then the center will gradually cook.
- You're aiming for a center that's fudgy but not raw—it should have a slight jiggle but set firm when cool.
- An instant-read thermometer inserted into the center should read 195–200°F (90–93°C) when done.
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Ready when: A toothpick inserted into the center comes out with a few moist crumbs (not wet batter); center has a slight jiggle; internal temperature reaches 195–200°F (90–93°C)
Tip: Do not cook on high—the edges will dry out and the center won't cook through evenly. Low heat is essential for fudgy bars.
9
Cool in the slow cooker
- Once done, turn off the slow cooker and remove the lid.
- Let the bars cool in the slow cooker for 15–20 minutes.
- This allows the structure to set slightly and prevents them from crumbling when you lift them out.
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Ready when: Bars are warm to the touch but no longer steaming; top is firm to the touch
Tip: Don't skip this cooling time—these bars are very delicate and will break if moved too soon.
10
Remove and cool completely
- Gently lift the parchment paper and bars out of the slow cooker using the extended sides of the paper as handles.
- Transfer to a wire rack or cutting board and let cool completely at room temperature for at least 30 minutes before cutting.
- The bars will continue to set as they cool.
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Ready when: Bars are cool to the touch and firm enough to cut without crumbling
Tip: Cooling completely is crucial for clean cuts. Use a sharp knife and wipe it between cuts for even edges.
11
Cut and serve
- Once completely cool, cut the square of bars into 16 equal pieces (4 cuts each direction makes 4×4 squares).
- Use a sharp knife dipped in hot water and wiped dry between cuts for clean edges.
- Store in an airtight container.
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Ready when: Bars are cut into even pieces with clean edges
Tip: A long, sharp knife dipped in hot water helps achieve clean cuts without dragging or crumbling.

Good to know

Tips

These bars are best served at room temperature or slightly chilled, as the fudgy texture is most pronounced when they're not warm. Cold bars are easier to slice cleanly.
The slow cooker's gentle, even heat creates an almost lava-cake-like center while setting the edges—this is what you want. Resist the urge to cook on high.
If your slow cooker runs very hot, start checking at 2 hours. Every slow cooker varies, and some cook hotter than others.
The stout beer's bitterness is intentional—it balances the richness of the chocolate and butter. If you prefer milder bars, reduce the espresso powder to ½ teaspoon.

Make ahead

Prepare the dry ingredients and measure everything up to 4 hours ahead. Refrigerate the batter in an airtight container for up to 1 day, then bring to room temperature before transferring to the slow cooker. The slow cooker cooking time remains the same.

Storage & reheating

Room temperature in an airtight container for up to 3 days. Refrigerate for up to 1 week in an airtight container—bars will firm up slightly when cold. Freeze individually wrapped in plastic wrap and stored in a freezer bag for up to 2 months. Thaw at room temperature for 30 minutes before serving. Do not reheat; these bars are best served at room temperature or slightly chilled.

Substitutions

stout beer (such as Guinness or a local dark stout), room temperature → Porter beer or dark ale. Any dark beer with roasted, malty notes will work. Avoid light beers, which lack depth.
dark chocolate chunks or roughly chopped dark chocolate (60–70% cacao) → Semi-sweet chocolate chunks or chopped bittersweet chocolate (70% cacao). 60–70% cacao is ideal for balance, but adjust to your sweetness preference.
instant espresso powder → 1 teaspoon strongly brewed and cooled espresso or ¼ teaspoon instant coffee. This deepens the chocolate flavor without adding actual beer bitterness. Optional but recommended.
all-purpose flour → Cake flour (use 1 cup + 2 tablespoons by volume). Cake flour creates an even more tender, fudgier crumb. Add 2 extra tablespoons to maintain structure.