Melt the Chocolate and Prepare Espresso: In a saucepan, heat 1 ½ cups of milk and 140 g of white chocolate over low heat until melted and smooth, about 5 minutes. Stir in 1 tablespoon of espresso powder until dissolved and cool to room temperature.

Preheat Oven and Prepare Pans: Preheat oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.

Mix Dry Ingredients: In a bowl, whisk together 2 ½ cups of flour, 2 ½ teaspoons of baking powder, and ½ teaspoon of salt.

Cream Butter and Sugar: Beat ¾ cup of butter and 1 ½ cups of sugar until light and fluffy, about 3-4 minutes. Add eggs and vanilla, mixing until combined.

Combine Wet and Dry Mixtures: Add the flour mixture alternately with the cooled chocolate-espresso mixture until smooth.

Bake the Cake Layers: Pour batter into prepared pans and bake for about 40 minutes, or until a toothpick comes out clean.

Make Swiss Meringue Buttercream: In a heatproof bowl, combine 3 egg whites and ½ cup sugar over simmering water, whisk until warm. Beat until stiff peaks form, then add 1 ½ cups of butter and 1 teaspoon of espresso powder.

Prepare White Chocolate Ganache: Heat 150 g of cream until boiling, pour over 200 g of chocolate, let sit, then stir until smooth.

Assemble the Cake: Spread ganache between layers, frost with remaining buttercream, and chill for 30 minutes.

Create Ganache Drip: Drizzle the ganache over the top of the cake for presentation.

Decorate and Serve: Decorate with optional elements like coffee beans and serve.