Preheat the oven to 350°F (175°C). Grease and line two 9-inch cake pans with parchment rounds.

In a large bowl, whisk together flour, sugar, cocoa powder, baking powder, baking soda, and salt.

In another bowl, combine eggs, milk, oil, and vanilla. Beat lightly to combine. Pour wet ingredients into dry and stir until mostly smooth — don’t overmix.

Carefully pour the boiling water into the batter and stir. The batter will be thin; that’s okay.

Divide batter evenly between the two pans. Bake for 28–32 minutes, or until a toothpick in the center comes out with a few moist crumbs. Cool in pans for 10 minutes, then invert onto wire racks to cool completely.

In a small saucepan, combine raspberries, sugar, and lemon juice. Cook over medium heat, mashing berries as they soften. Stir in the cornstarch slurry and cook 1–2 minutes until thickened. Remove from heat and let cool.

Place chopped chocolate in a bowl. Heat cream until it just simmers and pour over chocolate. Let sit for 1–2 minutes, then stir until glossy. Stir in butter for extra sheen if using.

Level the cakes if domed. Place one layer on your cake stand, spread half the ganache on top, spoon on the cooled raspberry filling, and spread evenly. Top with the second cake layer. Crumb-coat with a thin layer of ganache and chill for 15 minutes, then finish frosting with remaining ganache.

Add fresh raspberries on top and dust with cocoa powder or chocolate shavings. Chill slightly to set the ganache, or serve at room temperature.