Sourdough Discard Tiramisu Biscotti

Steps

1. 1

   Prep and preheat ovenOven 375°F / 190°C

   • Preheat your oven to 375°F (190°C).
   • Line a large baking sheet with parchment paper and set aside.
   • Ensure your sourdough discard and mascarpone cheese are both at room temperature—they should be soft and easily mixable.
   • If they've been refrigerated, remove them 30 minutes to 1 hour ahead of time.

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   Tip: Room-temperature ingredients mix smoothly; cold mascarpone will be lumpy and won't incorporate evenly.

2. 2

   Whisk eggs and sugar

   • In a medium bowl, whisk together the 3 large eggs and ¾ cup (150g) sugar.
   • Whisk vigorously for 2–3 minutes until the mixture is pale yellow, noticeably thicker, and increased in volume.
   • When you lift the whisk, the mixture should fall back to the surface in a slow ribbon that holds its shape briefly before disappearing.
   • This aeration is essential for the biscotti's light crumb.

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   Ready when: Mixture is pale, thick, and leaves a ribbon trail when the whisk is lifted

   Tip: This step incorporates air for lift; rushing it results in dense biscotti.

3. 3

   Fold in sourdough and mascarpone

   • Using a rubber spatula, gently fold the 1 cup (240g) sourdough discard into the egg mixture until mostly combined (a few streaks are fine).
   • Then fold in the ½ cup (115g) mascarpone cheese until just combined.
   • Work slowly to avoid deflating the aerated eggs.
   • The dough should look slightly streaky at this point; some unevenness is preferable to overdeveloping the mixture.

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   Ready when: Sourdough and mascarpone are mostly incorporated with a few visible streaks remaining

   Tip: Overmixing breaks down the mascarpone and deflates the eggs, resulting in dense biscotti; gentle folding is critical.

4. 4

   Mix dry ingredients

   • In another medium bowl, whisk together the 2¼ cups (270g) all-purpose flour, 2 tsp (5g) espresso powder, 1 tsp (5g) baking powder, and ¼ tsp (1g) kosher salt.
   • Use the back of a spoon to crush any small lumps of espresso powder against the bowl's side so it distributes evenly throughout the flour mixture—this prevents pockets of concentrated espresso flavor.

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   Ready when: Dry ingredients are evenly combined with no visible espresso powder lumps

5. 5

   Combine wet and dry, add vanilla

   • Gently fold the dry mixture into the wet mixture using slow, careful strokes of the spatula.
   • Stop as soon as no visible streaks of flour remain—overmixing toughens biscotti significantly.
   • Fold in the 1 tsp (5ml) vanilla extract with the final few strokes.
   • The dough will be thick and slightly sticky, similar to a thick chocolate chip cookie dough, which is exactly what you want.

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   Ready when: No visible dry flour streaks remain; dough is cohesive and thick

   Tip: Overmixing develops gluten and creates tough, dense biscotti; aim for 'just combined' and stop.

6. 6

   Shape into logs

   • Divide the dough in half.
   • On your parchment-lined baking sheet, shape each half into a log roughly 10 inches (25 cm) long and 2 inches (5 cm) wide.
   • Use your hands or a spatula to gently flatten the top slightly so it's level and even.
   • Space the two logs at least 2–3 inches (5–7 cm) apart to allow for slight expansion during baking.

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   Ready when: Two evenly shaped, flattened logs positioned on the baking sheet with adequate spacing

   Tip: Even thickness ensures both logs bake at the same rate; an uneven log will have over- and under-baked sections.

7. 7

   First bakeOven 375°F / 190°C

   • Place the baking sheet in the preheated 375°F (190°C) oven and bake for 25–30 minutes.
   • The logs should be golden brown on top, and a toothpick or skewer inserted in the center should come out clean or with just a few moist crumbs—not wet.
   • The logs will feel firm to the touch but still have a slight spring when pressed gently.
   • If the tops brown too quickly, loosely tent them with foil for the last 5 minutes.

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   Ready when: Logs are golden brown on top; toothpick inserted in center comes out mostly clean; logs feel firm but springy

   Tip: Underbaking leaves wet centers that won't crisp in the second bake; overbaking now creates a dense, hard final texture—aim for just-set.

8. 8

   Cool and slice logs

   • Remove the baking sheet from the oven and let the logs cool on the sheet for exactly 10 minutes.
   • They will firm up considerably during this time, making them much easier to slice without crumbling.
   • Once cooled slightly but still warm, use a serrated bread knife and a slow, gentle sawing motion to slice each log at a 45-degree angle into slices about ¾ inch (2 cm) thick.
   • You should get approximately 12 slices from each log, for roughly 24 biscotti total.
   • Stand each slice cut-side down on the parchment-lined baking sheet (you can reuse the same sheet or a fresh one).

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   Ready when: 24 slices arranged cut-side down on baking sheet; logs are cool enough to handle but still warm

   Tip: Slice while still warm; once completely cool, they're extremely hard to cut without shattering. A serrated knife and gentle sawing motion are essential.

9. 9

   Second bake, first sideOven 325°F / 165°C

   • Return the baking sheet to the oven at 325°F (163°C) and bake for 12–15 minutes.
   • The cut-facing-down side of each biscotto should turn light golden brown, and the edges should feel crispy to the touch.
   • The centers will still feel slightly soft—this is correct; they will crisp further in the next phase.

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   Ready when: Cut-facing-down side is light golden; edges feel crispy to the touch; centers still slightly soft

   Tip: Lower oven temperature prevents burning the already-cooked exterior while the interior dries out.

10. 10

    Flip and second bake, second sideOven 325°F / 165°C

    • Remove the baking sheet from the oven and, working quickly, carefully flip each biscotto so the other cut side faces down.
    • Use a small offset spatula or table knife to gently pry them up if any stick to the parchment.
    • Return the baking sheet to the 325°F (163°C) oven for another 12–15 minutes.
    • The second cut-facing-down side should also turn light golden.
    • When done, the biscotti should feel completely crispy throughout; if you tap one, it should sound hollow and feel hard like a hard biscuit.

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    Ready when: Both cut sides are light golden; biscotti are completely crispy and sound hollow when tapped

    Tip: They crisp more as they cool, so remove slightly underdone rather than overdone; overbaked biscotti become rock-hard.

11. 11

    Cool and dust

    • Remove from the oven and transfer the biscotti carefully to a wire rack to cool completely, about 15 minutes.
    • Handle them gently as they're still somewhat delicate just out of the oven.
    • As they cool, they'll firm up even more and become fully crisp.
    • Once completely cool, lightly dust them with the 2 tbsp (12g) unsweetened cocoa powder.
    • If desired, first whisk the 1 tsp (2.5g) optional espresso powder together with the cocoa powder for a more pronounced tiramisu flavor, then dust evenly.
    • Use a fine-mesh sieve or sifter to apply the cocoa evenly, or place the biscotti in a container with the cocoa powder and gently shake to coat.

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    Ready when: Biscotti are completely cool, fully crispy, and evenly dusted with cocoa (and espresso if using)

    Tip: Dust right before serving to keep cocoa from absorbing moisture; dusted biscotti last about 2–3 days before cocoa becomes damp.