In a medium saucepan, heat the milk over medium heat until it’s steaming but not boiling. Remove from heat and set aside.

In a medium bowl, whisk together the egg yolks, sugar, and cornstarch until smooth and pale. Slowly whisk in about 1/4 cup of the hot milk to temper the eggs, then gradually whisk in the rest of the milk.

Pour the mixture back into the saucepan and cook over medium heat, whisking constantly, until it thickens and bubbles (about 2-3 minutes). Once thickened, cook for an additional minute while whisking to ensure it’s fully set.

Remove from heat and stir in the vanilla extract and butter until smooth. Transfer the cream to a bowl, cover with plastic wrap pressed directly onto the surface to prevent a skin, and chill for at least 2 hours or until fully set.

Preheat the oven to 350°F (175°C). Grease and line the bottom of a 9-inch deep cake pan with parchment paper.

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

In a large bowl, beat the eggs and sugar with a mixer on high speed until pale, thick, and fluffy (about 5 minutes). The mixture should form ribbons when the beaters are lifted.

Heat the milk and butter together in a small saucepan or microwave until the butter melts. Gradually fold the dry ingredients into the egg mixture, alternating with the warm milk mixture, until just combined. Stir in the vanilla extract.

Pour the batter into the prepared pan and smooth the top. Bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean. Let the cake cool in the pan for 10 minutes, then turn it out onto a wire rack to cool completely. Peel off the parchment paper.

Once the cake is completely cool, use a serrated knife to carefully slice it horizontally into two even layers. If the cake has a domed top, carefully trim it flat before slicing into two pieces.

Place the bottom cake layer on a serving plate or cake stand. Stir the chilled pastry cream to loosen it slightly, then spread it evenly over the top of the cake, leaving a small border around the edges. Place the second cake layer on top, bottom side up, to create a flat surface. Press gently to adhere. Chill the assembled cake for at least 1 hour to firm up.

Heat the cream in a small saucepan or microwave until steaming. Pour the hot cream over the chopped chocolate in a bowl. Let it sit for 1-2 minutes, then stir until smooth and glossy. If using, stir in the corn syrup for extra shine. Let the ganache cool slightly until it thickens but is still pourable.

Pour the ganache over the top of the chilled cake, letting it drip down the sides naturally. Use a spatula to smooth the top if needed. Chill the cake for 30 minutes to set the ganache.

Once the ganache is set, slice the cake with a sharp knife (warm the knife under hot water and dry it for cleaner cuts). Serve chilled or at room temperature. Enjoy!