Preheat oven to 350°F (177°C). Grease and flour two 9-inch round cake pans.
In a large bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt.
Add the milk, vegetable oil, eggs, and vanilla to the dry ingredients. Mix until well combined.
Slowly add boiling water to the batter, mixing gently until smooth. The batter will be thin.
Divide the batter evenly between the prepared cake pans. Bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean.
Cool the cakes in the pans for 10 minutes, then transfer to a wire rack to cool completely.
For the ganache, heat the heavy cream in a small saucepan over medium heat until simmering. Pour over the chopped chocolate in a bowl. Let sit for 5 minutes, then whisk until smooth.
Spread a layer of ganache on top of one cake layer. Add a layer of raspberries. Top with the second cake layer and frost the entire cake with ganache.
Garnish with additional raspberries if desired. Chill for 1 hour before serving.