Preheat the oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.

In a medium bowl, whisk together the flour, baking powder, and salt.

In a large bowl, cream the softened butter and 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, beginning and ending with the dry ingredients. Mix until just combined.

Divide the batter evenly between the prepared pans and smooth the tops.

Bake for 25–30 minutes, or until a toothpick inserted into the center comes out clean.

Remove from the oven and let the cakes cool in the pans for 10 minutes. Then, transfer to a wire rack to cool completely.

In a medium saucepan, heat the half-and-half over medium heat until it begins to simmer.

In a separate bowl, whisk together the egg yolks, sugar, and flour until smooth.

Gradually add about ½ cup of the hot half-and-half to the egg mixture, whisking constantly to temper the eggs.

Pour the tempered egg mixture back into the saucepan with the remaining half-and-half. Cook over medium heat, whisking constantly, until the mixture thickens and comes to a boil.

Remove from heat and stir in the vanilla extract.

Transfer the pastry cream to a bowl, cover with plastic wrap, and refrigerate until chilled.

In a small saucepan, heat the heavy cream and corn syrup over medium heat until it begins to simmer.

Remove from heat and add the chopped chocolate. Let it sit for 2–3 minutes, then stir until smooth and glossy.

Allow the ganache to cool slightly before using.

 

Place one cake layer on a serving platter. Spread the chilled pastry cream evenly over the top.

Place the second cake layer on top of the pastry cream.

Pour the cooled chocolate ganache over the top, spreading it evenly to cover the entire cake.

Refrigerate the assembled cake for at least 2 hours before serving to allow the flavors to meld and the ganache to set.