Preheat your oven to 350°F. Grease and flour two 9-inch round cake pans to prepare them for the batter.

In a large bowl, sift together the all-purpose flour, baking powder, baking soda, salt, and cocoa powder. Set aside.

In another bowl, using an electric mixer, cream the softened butter and granulated sugar until light and fluffy. Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract.

Gradually add the dry ingredients to the wet mixture, alternating with the milk. Mix until just combined. Divide the batter evenly between the prepared cake pans and smooth the tops. Bake for 25-30 minutes or until a toothpick inserted into the center comes out clean.

Allow the cakes to cool in the pans for 10 minutes before transferring them to a wire rack to cool completely.

In a small saucepan, heat the heavy cream over medium heat until it just begins to simmer. Do not let it boil.

Place the chopped dark chocolate in a heatproof bowl. Pour the hot cream over the chocolate and let it sit for a few minutes. Stir until the mixture is smooth and glossy. Stir in the vanilla extract. Allow the ganache to cool to a spreadable consistency.

Place one cake layer on a serving platter. Spread a generous amount of ganache on top. Place the second layer on top and cover the entire cake with the remaining ganache, smoothing it with a spatula for a glossy finish.

Let the cake sit at room temperature for a few hours before serving to allow the flavors to meld. Slice and enjoy with a side of ice cream or whipped cream.

Store any leftover cake in an airtight container at room temperature for up to three days, or refrigerate for up to a week.