Preheat your oven to 350°F (175°C). In a large mixing bowl, whisk together 1 ½ cups of all-purpose flour, 1 ½ teaspoons of baking powder, and a pinch of salt until well combined. In another bowl, blend 3 large eggs, 1 cup of milk, and 1 teaspoon of vanilla extract. Gradually combine the wet and dry ingredients, mixing until smooth. Pour the batter into two greased 9-inch round cake pans and bake for 25–30 minutes until golden brown and a toothpick inserted into the center comes out clean. Allow the cakes to cool completely on a wire rack.

While the cakes cool, start crafting your custard. In a saucepan over medium heat, warm 2 cups of milk until just bubbling, then remove from heat. In a separate bowl, whisk together 4 egg yolks and ½ cup of granulated sugar until the mixture becomes pale. Gradually pour the heated milk into the yolk mixture while whisking vigorously to temper the eggs. Return the mixture to the saucepan and cook over medium heat, stirring constantly until thickened—about 5–7 minutes. Once thick, remove from heat and let it cool slightly; stir in 1 teaspoon of vanilla extract.

To make the glossy ganache that tops your Boston Cream Pie, start by heating 1 cup of heavy cream in a small saucepan over medium heat until it begins to bubble. Remove from heat and pour over 8 ounces of chopped chocolate in a bowl. Allow it to sit for 5 minutes without stirring, then gently mix until you achieve a smooth, shiny ganache. Set aside to cool and thicken before using.

Place one layer of cooled cake on a cake plate or serving platter. Spread a generous layer of the vanilla custard evenly on top, making sure to cover it right to the edges. Carefully place the second cake layer on top of the custard. Pour the cooled chocolate ganache over the entire cake, ensuring it drips down the sides.

For the best flavors and textures, chill the assembled Boston Cream Pie in the refrigerator for at least 2 hours or until the ganache is set. Slice the pie with a sharp knife, wiping it clean between cuts for neat slices. Serve chilled, perhaps garnished with whipped cream or fresh berries.