Moist 6-inch Chocolate Cake (Single layer)

Ingredients

• 83 g all-purpose flour
• 25 g cocoa powder (natural or dutch processed)
• 1/2 teaspoon baking powder
• 1/4 teaspoon baking soda
• 1/4 teaspoon salt
• 60 g whole milk
• 1/2 teaspoon Apple cider vinegar (or white vinegar or lemon juice)
• 1 large egg
• 66 g granulated sugar
• 50 g soft brown sugar
• 45 g oil (vegetable or melted coconut oil)
• 1/2 teaspoon vanilla paste or extract
• 60 g hot coffee (or use hot water)
• 113 g semi-sweet chocolate
• 2 large egg whites (60g/2 oz)
• 66 g granulated sugar
• Pinch salt
• 170 g unsalted butter (softened to room temperature.)
• 1/2 teaspoon vanilla paste (or extract)

Instructions

1. 1

   --- Cake ---

2. 2

   Preheat the oven to 350°F (180°C). Grease and line a 6x3-inch round cake pan with parchment paper.

3. 3

   Whisk together the flour, cocoa powder, baking powder, baking soda, and salt in a bowl. Set aside. 83 g all-purpose flour, 25 g cocoa powder, 1/2 teaspoon baking powder, 1/4 teaspoon baking soda, 1/4 teaspoon salt

4. 4

   Measure the milk, add the vinegar, stir, and leave to sit for 2 minutes. 60 g whole milk, 1/2 teaspoon Apple cider vinegar

5. 5

   In a separate bowl, whisk together the egg, sugars, oil, and vanilla. 1 large egg, 66 g granulated sugar, 50 g soft brown sugar, 45 g oil, 1/2 teaspoon vanilla paste or extract

6. 6

   Add the dry ingredients to the wet in thirds, alternating with the milk mixture, folding gently with a spatula after each addition.

7. 7

   Pour in the hot coffee and fold until just combined. Do not overmix. 60 g hot coffee

8. 8

   Pour the batter into the prepared pan and bake for 30 to 35 minutes, until a skewer inserted in the center comes out clean.

9. 9

   Run a knife around the edge to loosen. Cool in the pan for 15 minutes, then turn out onto a wire rack and cool completely before frosting.

10. 10

    --- Chocolate Swiss Meringue Buttercream ---

11. 11

    Melt the chocolate in a microwave-safe bowl in 20 to 30 second bursts, stirring after each, until fully melted. Set aside to cool to room temperature. 113 g semi-sweet chocolate

12. 12

    In a clean, grease-free metal bowl (either the bowl of your stand mixer or another metal bowl), combine the egg whites, sugar, and salt. Set over a pot with 1 inch of gently simmering water, making sure the bottom of the bowl does not touch the water. Do not use a glass or ceramic bowl as it can crack or shatter. Whisk constantly until all the sugar has dissolved and the mixture reaches 160°F (71°C) on an instant-read thermometer. 2 large egg whites, 66 g granulated sugar, Pinch salt

13. 13

    If you used a separate metal bowl, transfer the mixture to the bowl of your stand mixer now. Fit the whisk attachment and beat on medium-high speed until stiff, glossy peaks form and the bowl is completely cool to the touch, about 8 to 10 minutes.

14. 14

    With the mixer running on medium speed, add the softened butter one cube at a time, waiting until each cube is fully incorporated before adding the next. The mixture may look curdled at this stage. Keep beating and it will come together.170 g unsalted butter

15. 15

    Beat in the cooled melted chocolate and vanilla until the buttercream is smooth and fluffy. 1/2 teaspoon vanilla paste

16. 16

    Switch to the paddle attachment and beat on low speed for 5 to 10 minutes to remove the larger air bubbles.

17. 17

    --- Assemble ---

18. 18

    Spread the buttercream generously over the top and sides of the cooled cake. Decorate as desired. Store leftover cake at room temperature in an airtight container for up to 3 days, or refrigerate for up to 5 days.