Preheat your oven to 350°F (175°C) and grease two 9-inch round cake pans. In a bowl, whisk together flour, baking powder, and salt. In another bowl, combine eggs, milk, and vanilla extract, then blend into the dry ingredients until smooth. Pour the batter evenly into the prepared pans and bake for 25–30 minutes, or until a toothpick inserted in the center comes out clean. Cool in pans for 10 minutes, then transfer to wire racks to cool completely.

In a medium saucepan, heat 2 cups of milk over medium heat until steaming but not boiling. While it heats, whisk egg yolks with sugar until pale. Gradually mix in the warm milk to temper the eggs, then return the mixture to the saucepan. Cook over medium-low heat, stirring constantly until thickened, about 5–7 minutes. Once thick and smooth, remove from heat and let cool.

In a small saucepan, heat 1 cup of heavy cream over medium heat until it just begins to bubble. Remove from heat and pour the hot cream over 8 ounces of chopped chocolate in a bowl. Let it sit for 5 minutes to soften, then whisk until the mixture is glossy and well combined.

On a serving platter, lay one cake layer down. Spread the cooled custard evenly over the first layer, then carefully place the second cake layer on top. Drizzle the silky chocolate ganache over the top, allowing it to cascade down the sides. Chill the assembled pie in the refrigerator for at least 30 minutes before slicing.

After chilling, slice into generous pieces and serve chilled. Garnish with a dusting of powdered sugar or a dollop of whipped cream if desired.