Preheat oven to 350F. Melt butter in microwave (about 45 sec).

Lightly beat eggs in a medium bowl. Stir in sugar, vanilla extract, and warm melted butter

Add flour, cocoa powder, salt, and baking powder. Whisk until combined, do not overmix.

Spread batter into a greased 8x8 pan and bake for 30 minutes or until a toothpick comes out clean