INGREDIENTS
•
5 eggs, separated
•
Butter, softened
•
Sugar
•
1/2 cup sugar, divided
•
2 tablespoons unsweetened cocoa powder
•
3 tablespoons all-purpose flour
•
1/8 teaspoon salt
•
1/2 cup whole milk
•
1/4 cup leftover strong coffee (or 1 teaspoon instant espresso coffee powder dissolved in 1/4 cup water)
•
6 ounces bittersweet chocolate, chopped
•
1/4 teaspoon cream of tartar
•
Powdered sugar and/or unsweetened cocoa powder