Two-Ingredient Nutella Brownies . The detailed recipe instructions couldn't be simpler: Start by beating 4 whole eggs in a stand mixer for 6 to 8 minutes. You can also use a hand mixer, but a full-size mixer will incorporate more air into the eggs and leaves you free to move about the kitchen while it whips—plus, no elbow grease. Line one 9x9-inch baking pan with foil and spray with cooking spray. In a saucepan over medium-heat, melt butter. Stir in sugar until dissolved. Remove mixture from heat. Gradually pour melted butter into beaten eggs, whisking constantly, until mixture is fully incorporated. Stir in vanilla. 098pw.