Preheat oven to 350°F (175°C). Grease two round cake pans and dust with flour.
In a bowl, whisk together flour, baking powder, and salt; set aside.
In another bowl, beat softened butter and sugar until light and fluffy. Add eggs one at a time, followed by milk and vanilla extract until blended.
Gradually mix in dry ingredients until just combined. Pour batter into prepared pans.
Bake for 25-30 minutes or until a toothpick comes out clean. Cool completely before assembling.
For the pastry cream, heat heavy cream in a saucepan; whisk in vanilla and cornstarch until thickened.
Slice each cake in half horizontally. Spread pastry cream between layers and stack them up. Pour chocolate ganache over the top before serving.
