Preheat your oven to 350°F (175°C). Grease the cake pans and line the bottoms with parchment paper.
In a large mixing bowl, sift together the flour, sugar, cocoa powder, baking powder, baking soda, and salt.
In a separate bowl, whisk together the eggs, milk, vegetable oil, and vanilla extract until well combined.
Gradually add the wet ingredients to the dry ingredients, mixing until just combined. Carefully stir in the boiling water until the batter is smooth. The batter will be thin.
Gently fold in the raspberries into the batter. Divide the batter evenly between the prepared cake pans.
Bake in the preheated oven for 25 to 30 minutes or until a toothpick inserted in the center comes out clean. Allow the cakes to cool in the pans for about 10 minutes before transferring to a cooling rack to cool completely.
For the ganache, heat the heavy cream in a saucepan over medium heat until it begins to simmer. Remove from heat and add the chopped dark chocolate. Let it sit for a minute, then whisk until smooth.
Once the cakes are cool, place one layer on a serving plate and spread a layer of ganache over the top. Place the second layer on top and pour the remaining ganache over the top, allowing it to drip down the sides.
Garnish with additional fresh raspberries if desired. Allow the ganache to set for a few minutes before slicing and serving.