5 large eggs
4 teaspoons plus ¾ cup sugar, divided
½ cup quality cocoa powder
6 Tablespoons all-purpose flour
¼ teaspoon salt
1 ½ cups fat-free milk
2 Tablespoons butter, melted
1 ½ teaspoons vanilla extract
chocolate syrup, chocolate shavings (optional garnish)
Preheat oven to 350°. Separate eggs and set aside. Coat oven safe mugs with non-stick spray, add a pinch of sugar to the bottom. In a small saucepan over medium heat, combine cocoa, flour, salt, and sugar. Whisk in milk, bring to a boil, stirring constantly. Cook until thickened, about 2 minutes. Stir in butter, transfer mixture to a large bowl. Stir a small amount of hot cocoa mixture into egg yolks, then pour into cocoa mixture, stirring constantly. Add vanilla, let cool slightly.
In a large bowl, beat egg whites until stiff peaks form. Gently fold a quarter of the egg whites into the chocolate until combined. Fold in remaining egg whites. Spoon batter into mugs, bake until tops are puffed, and center is almost set, 15-20 minutes. Garnish, serve immediately!