Decadent Chocolate Custard Cake

Directions:
1. Preheat your oven to 325°F (170°C). Grease and line an 8×8-inch baking pan with parchment paper.
2. For the egg yolk mixture, in a bowl, beat the egg yolks with sugar and vanilla until they’re light and creamy. Then, add the melted butter, and sift in the flour and cocoa, mixing until just combined. Gradually pour in the lukewarm milk while stirring.
3. In another bowl, whip the egg whites with sugar and salt until they form stiff peaks.
4. Gently fold the whipped egg whites into the yolk mixture in two additions.
5. Pour the batter into the prepared pan and bake for 40-45 minutes. If you notice the top browning too quickly, you can cover it loosely with foil.
6. Once baked, turn off the oven and let the cake sit inside with the door slightly open for 5 minutes. Then, let it cool in the pan before transferring to the refrigerator for 1 hour to set.
7. To serve, lift the cake from the pan using the parchment overhang, slice it, and if desired, dust with cocoa or powdered sugar before serving.