Step 1: Prepare the Cake Batter

1. Preheat your oven to 350°F (175°C). Grease and line two 9-inch round cake pans with parchment paper.
2. In a large mixing bowl, sift together the flour, sugar, cocoa powder, baking powder, baking soda, and salt.
3. In another bowl, whisk together the eggs, milk, vegetable oil, and vanilla extract.
4. Gradually add the wet ingredients to the dry ingredients and mix until smooth.
5. Stir in the boiling water last. The batter will be thin, but this secures a moist cake.
6. Divide the batter evenly between the prepared pans and smooth the tops.

Step 2: Bake the Cakes

1. Bake the cakes in the preheated oven for 30-35 minutes, or until a toothpick inserted into the center comes out clean.
2. Let the cakes cool in the pans for 10 minutes, then transfer them to a wire rack to cool completely.

Step 3: Make the Ganache

1. Heat the heavy cream in a small saucepan over medium heat until it just begins to simmer. Do not let it boil.
2. Pour the hot cream over the chopped dark chocolate in a bowl. Let it sit for 2 minutes to melt.
3. Stir until the ganache is smooth and glossy. Add the butter for extra shine, if desired. Let it cool to a spreadable consistency.

Step 4: Assemble the Cake

1. If needed, level the tops of the cakes with a serrated knife to secure flat layers.
2. Place one cake layer on a serving plate. Spread a thin layer of ganache over the top, then add a layer of sliced strawberries.
3. Place the second cake layer on top and spread ganache over the top and sides, smoothing it with an offset spatula.

Step 5: Decorate the Cake

1. Arrange whole strawberries on top of the cake for decoration.
2. Add optional garnishes like chocolate curls or sprinkles for extra flair.

Step 6: Serve and Enjoy

1. Let the cake set for at least 30 minutes before slicing to allow the ganache to firm up.
2. Slice and serve your delicious chocolate strawberry cake with a side of whipped cream or fresh strawberries if desired.