Melt the Chocolate and Butter

Place chocolate chips and butter in a mixing bowl.

Heat a pot of water until it simmers, then place the bowl over the hot water to melt them. Stir continuously until smooth. Remove from heat and let cool.

Whisk the Eggs and Sugar

In a clean mixing bowl, whisk the eggs and sugar until well combined.

Sift and Mix the Dry Ingredients

Sift the cake flour, cocoa powder, and baking powder together.

Gradually fold the dry ingredients into the egg mixture. Be careful not to overmix.

Incorporate the Chocolate Butter Mixture

Pour the cooled chocolate and butter mixture into the batter. Gently fold until smooth and well combined.

Bake the Brownies

Pour the batter into a parchment-lined mold and smooth the surface.

Preheat the oven to 170°C (340°F) for 10-15 minutes.

Bake in the middle rack for 25 minutes.

Remove from the oven and let cool on a wire rack.

Whisk the Egg Yolk and Sugar

In a heatproof bowl, add the egg yolk and sugar.

Place the bowl over a pot of simmering water, whisking with an electric mixer on low speed until the mixture turns pale and fluffy.

Add Mascarpone Cheese

Add mascarpone cheese to the egg mixture.

Beat on low speed until smooth and fully combined.

Whip the Heavy Cream

In a separate bowl, whip the heavy cream using an electric mixer.

Start on low speed, then gradually increase speed until soft peaks form.

Combine the Mixtures

Add the whipped cream to the mascarpone mixture in two batches, folding gently with a spatula until smooth and fully combined.

Layer the Tiramisu on the Brownie

Transfer the tiramisu mixture into a piping bag and pipe it evenly over the cooled brownie.

Use a spatula to smooth the surface.

Chill to Set

Refrigerate the tiramisu brownies for at least 4 hours to allow the layers to set properly.

Dust with Cocoa Powder

Before serving, dust an even layer of cocoa powder over the surface using a fine sieve.