Oat and Apple Sheet Cake with Cinnamon Sugar

Name: Oat and Apple Sheet Cake with Cinnamon Sugar
Prep time: 20 min
Cook time: 35 min
Total time: 55 min
Yield: 12 servings
Cuisine: American
Ingredients: 8 tablespoons (113 g) unsalted butter, softened, softened to room temperature; 1 cup (220 g) packed light brown sugar; 2 (100 g) large eggs, at room temperature; 1½ teaspoons (7½ ml) vanilla extract; 1½ cups (188 g) all-purpose flour; 1 cup (100 g) rolled oats (old-fashioned); 1½ teaspoons (7½ g) baking powder; ½ teaspoon (3 g) salt; 1½ teaspoons (4½ g) ground cinnamon; ¼ teaspoon (½ g) ground nutmeg (optional); 2 medium (300 g) tart apples (Granny Smith or Honeycrisp), peeled, cored, and chopped into ½-inch pieces; 3 tablespoons (43 g) unsalted butter, melted; ⅓ cup (73 g) packed light brown sugar; 1 tablespoon (3 g) ground cinnamon; ⅛ teaspoon (¾ g) salt

From the MyKitchenBank Kitchen

A moist, tender sheet cake studded with tart apples and rolled oats, topped with a buttery cinnamon-sugar crunch. Tender crumb from brown sugar and butter, with the heartiness of oats and fresh apple pieces throughout. Perfect for breakfast, brunch, or casual dessert.

Prep: 20 min
Cook: 35 min
Wait: 15 min
Total: 1 hr 10 min
Makes: 1 sheet cake (12 servings)

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Ingredients

12 servings

8 tablespoons (113 g) unsalted butter, softened, softened to room temperature
1 cup (220 g) packed light brown sugar
2 (100 g) large eggs, at room temperature
1½ teaspoons (7.5 ml) vanilla extract
1½ cups (188 g) all-purpose flour
1 cup (100 g) rolled oats (old-fashioned)
1½ teaspoons (7.5 g) baking powder
½ teaspoon (3 g) salt
1½ teaspoons (4.5 g) ground cinnamon
¼ teaspoon (0.5 g) ground nutmeg (optional)
2 medium (300 g) tart apples (Granny Smith or Honeycrisp), peeled, cored, and chopped into ½-inch pieces
For the topping
3 tablespoons (43 g) unsalted butter, melted
⅓ cup (73 g) packed light brown sugar
1 tablespoon (3 g) ground cinnamon
⅛ teaspoon (0.8 g) salt

Equipment (8)

9×13-inch (23×33 cm) baking pan
Medium mixing bowl
Large mixing bowl
Whisk
Wooden spoon or spatula
Measuring cups and spoons
Small bowl (for topping)
Cooling rack (optional)

Steps

Before you start

Preheat the oven to 350°F (175°C)
Grease and line a 9×13-inch (23×33 cm) baking pan with parchment paper
Bring eggs to room temperature for 30 minutes if you have time
Peel, core, and chop apples just before mixing the batter to prevent browning

1
Combine dry ingredients
- In a medium mixing bowl, whisk together the all-purpose flour, rolled oats, baking powder, salt, ground cinnamon, and nutmeg (if using).
- Set aside.
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Ready when: Mixture is evenly combined and no flour streaks remain
Tip: Whisk the dry ingredients thoroughly to distribute the baking powder and spices evenly throughout the cake
2
Cream butter and sugar
- In a large mixing bowl, beat the softened butter and 1 cup (220 g) brown sugar together on medium speed for 2–3 minutes until the mixture is light, fluffy, and pale in color.
- This incorporates air into the batter for a tender crumb.
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Ready when: Mixture is noticeably lighter in color and has increased in volume
Tip: Do not skip the creaming step—it's essential for a tender, well-aerated cake
3
Add eggs and vanilla
- Add the 2 room-temperature eggs one at a time to the creamed butter and sugar, beating well after each addition (about 30 seconds per egg).
- Then add the vanilla extract and beat for another 30 seconds until fully incorporated.
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Ready when: Mixture is smooth and homogeneous with no streaks of egg white visible
Tip: Adding eggs slowly prevents the batter from curdling; cold eggs can cause lumps
4
Fold in dry ingredients and apples
- Using a spatula or wooden spoon, gently fold the dry ingredient mixture into the wet ingredients in two additions, stirring just until no flour streaks remain.
- Be careful not to overmix, as this can toughen the cake.
- Fold in the chopped apple pieces until evenly distributed.
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Ready when: No flour streaks visible; apple pieces are distributed throughout the batter
Tip: Fold gently to avoid deflating the air you incorporated during creaming—a lumpy batter is better than an overmixed one
5
Prepare cinnamon-sugar topping
- In a small bowl, combine the 3 tablespoons (43 g) melted butter, ⅓ cup (73 g) brown sugar, 1 tablespoon (3 g) cinnamon, and ⅛ teaspoon (0.75 g) salt.
- Stir until the mixture resembles wet sand with small clumps.
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Ready when: Butter is evenly distributed and no dry brown sugar remains
Tip: Make the topping while the oven preheats so it's ready to sprinkle on immediately before baking
6
Transfer batter and add topping
- Pour the batter into your prepared 9×13-inch (23×33 cm) pan and spread it evenly with a spatula.
- Sprinkle the cinnamon-sugar topping evenly over the entire surface, pressing it gently so it adheres to the batter.
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Ready when: Batter is level and topping is evenly distributed
Tip: Spread the batter to the edges and corners to ensure even baking and avoid thick edges
7
Bake the cakeOven 350°F / 175°C
- Place the pan in your preheated 350°F (175°C) oven and bake for 32–38 minutes.
- The cake is done when a wooden toothpick inserted into the center comes out with just a few moist crumbs (not wet batter) and the top is golden brown.
- The edges will pull slightly away from the pan sides.
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Ready when: A toothpick inserted in the center comes out with only a few moist crumbs; top is golden brown
Tip: Ovens vary, so begin checking at 32 minutes. If the toothpick is clean, the cake may be slightly dry; if it's very wet, continue baking for 2–3 minutes
8
Cool the cake
- Remove the pan from the oven and set it on a cooling rack or trivet.
- Let the cake cool in the pan for 15 minutes.
- This allows the structure to set so it won't fall apart when you remove it.
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Ready when: Cake is still warm to the touch but no longer steaming
Tip: Do not skip this cooling time or the cake may crack or crumble when removed from the pan
9
Serve
- Cut the cake into 12 even pieces and serve warm or at room temperature.
- The cinnamon-sugar topping will have crisped up and will provide a pleasant crunch against the moist cake.
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Tip: A sharp serrated knife dipped in hot water makes for cleaner cuts

Good to know

Tips

To prevent apple pieces from sinking to the bottom during baking, toss the chopped apples lightly in 1 tablespoon of flour before folding them into the batter.
For a deeper cinnamon flavor, increase the cinnamon in the batter to 2 teaspoons and the topping to 1½ tablespoons.
If you prefer a cake with more distinct apple texture, use slightly larger apple chunks (about ¾-inch pieces) and don't chop them as finely.
Serve with a dollop of Greek yogurt, whipped cream, or a drizzle of maple syrup for a more indulgent breakfast or brunch treat.

Make ahead

You can prepare the dry ingredients 1 day ahead and store them in an airtight container. Mix the wet ingredients and apples only just before baking. The baked cake keeps well, so it can be made up to 2 days ahead and covered tightly at room temperature.

Storage & reheating

Room temperature: Cover tightly with plastic wrap or place in an airtight container for up to 3 days. The cake will soften slightly as it sits, which adds to its tenderness. Refrigerator: Store in an airtight container for up to 5 days; the cake may become slightly denser but remains moist. To serve chilled, let it come to room temperature for 30 minutes or warm individual pieces in the microwave for 15–20 seconds. Freezer: Wrap cooled cake slices individually in plastic wrap and foil, or place the whole cake in a freezer-safe container with parchment between layers, for up to 3 months. Thaw at room temperature for 1–2 hours before serving.

Substitutions

tart apples (Granny Smith or Honeycrisp) → sweeter apple varieties (Gala, Fuji, or Pink Lady). The cake will be slightly sweeter but still delicious; reduce the vanilla extract by ¼ teaspoon if using very sweet apples
rolled oats (old-fashioned) → old-fashioned oats blended into a coarser flour, or use quick oats (reduce to ¾ cup) for a denser crumb. Quick oats will integrate more fully into the cake; the texture will be less chunky
packed light brown sugar → granulated white sugar plus 1 tablespoon molasses or honey. The molasses adds brown sugar's moisture and flavor; whisk it in during the creaming step
unsalted butter, softened → coconut oil or vegetable oil. Use the same weight; the cake will be slightly more tender but less rich