Preheat your oven to 350°F (175°C). Lightly grease a 9×9-inch square baking pan or line with parchment paper. Set aside.

In a small bowl, sift together the flour and baking powder. Mix to combine and set aside.

In a stand mixer fitted with a whisk attachment (or using a hand mixer), beat the eggs on high speed for approximately 3 to 4 minutes, or until thick and pale in color. Reduce speed to medium and gradually add in the sugar, continuing to beat for an additional 4 to 5 minutes until light and fluffy.

With the mixer on low, slowly add the flour and baking powder mixture to the egg and sugar blend. Mix just until a smooth batter forms, ensuring not to overmix.

In a small saucepan over medium heat, combine the milk and butter. Heat until the butter is fully melted and the mixture is hot, but not boiling.

Carefully pour the hot milk mixture into the batter and mix until fully incorporated. The batter will be thin and smooth.

Transfer the batter to the prepared pan and bake for 20 to 25 minutes, or until a toothpick inserted in the center comes out clean. Allow the cake to cool completely on a wire rack before adding the ganache.

Place the chocolate chips in a heat-safe bowl. In a separate container, heat the cream in the microwave until it just begins to boil, approximately 90 seconds. Pour the hot cream over the chocolate chips, cover the bowl, and let sit for 1 minute. Stir until the chocolate is fully melted and the ganache is smooth and glossy. Stir in vanilla extract, if using.

Once the cake has cooled, evenly spread the ganache over the surface using a spatula or the back of a spoon. Allow the ganache to set before serving.