1. Preheat & Prep

• Preheat oven to 350°F (175°C).

• Grease and line a 9×5-inch loaf pan with parchment paper, leaving some overhang for easy removal.

2. Mix the Base Batter

1. In a medium bowl, whisk together flour, baking powder, baking soda, and salt.

2. In a large bowl, cream butter and sugar until light and fluffy (about 2–3 minutes).

3. Beat in eggs one at a time, then stir in vanilla.

4. Alternately mix in the dry ingredients and milk, beginning and ending with dry.

   • (Mix just until combined — don’t overbeat.)

3. Divide & Flavor

• Split the batter evenly into two bowls.

For the chestnut batter: Stir in chestnut purée and rum or extra vanilla.
For the chocolate batter: Stir in cocoa, melted chocolate, and milk until smooth.

4. Create the Swirl

• Spoon alternating dollops of each batter into the loaf pan (like a checkerboard pattern).

• Use a butter knife or skewer to gently swirl through the batters — just a few figure-eights to marble it.

5. Bake

• Bake for 45–55 minutes, or until a toothpick inserted in the center comes out clean.

• Cool in the pan for 10 minutes, then lift out and cool completely on a wire rack.

6. Serve

• Dust with powdered sugar or drizzle with melted chocolate.

• Delicious slightly warm or at room temperature.