Microwave Brownies with Cocoa Powder (No Mix!)

Ingredients

• 2 large eggs
• 3/4 cup sugar
• 1/2 teaspoon salt
• 1 teaspoon vanilla extract
• 1/2 cup melted unsalted butter
• 3/4 cup all-purpose flour
• 1/2 cup cocoa powder (not Dutched)
• 1 teaspoon instant espresso (optional)
• 1/4 cup chopped semi-sweet chocolate or chocolate chips
• 1/4 cup chopped nuts (toasted nuts (peanuts, pecans, walnuts, etc.))
• pinch cinnamon