1. Prepare the sourdough starter discard by whisking it briefly to loosen and bring to room temperature.

2. Preheat the oven to 350°F (175°C) and grease a 10–12 cup Bundt pan, dusting with cocoa powder.

3. In a bowl, sift together all-purpose flour, cocoa powder, baking soda, baking powder, and salt.

4. In another bowl, whisk granulated sugar, brown sugar, eggs, vegetable oil, vanilla extract, sourdough discard, buttermilk, and peppermint extract until smooth.

5. Gradually fold the dry ingredients into the wet mixture until just combined, then fold in the semi-sweet chocolate chips.

6. Pour the batter into the prepared pan, tap gently to remove air bubbles, and bake for 45–50 minutes until a skewer comes out with moist crumbs.

7. Cool the cake in the pan for 15 minutes, then invert onto a wire rack and let cool completely.

8. Heat heavy cream until steaming and pour over chopped dark chocolate; let sit for 1 minute, stir until smooth, and whisk in butter.

9. Place the cooled cake on a wire rack over parchment paper and pour the ganache over the top, adding optional crushed peppermint or white chocolate drizzle.

10. Let the ganache set at room temperature for 1 hour before slicing and serving.