Ingredients:
Nonstick cooking spray
4 eggs
1/2 cup salted butter, softened
1 cup granulated sugar
1 tsp. baking powder
1/2 tsp. salt
1 1/2 tsp. vanilla
1 1/2 cups all-purpose flour
1 cup bittersweet chocolate chips
1 cup miniature marshmallows
1/2 cup chopped pecans, toasted (optional)
1 cup packed brown sugar
Instructions:
Preheat oven to 350°F. Lightly coat a 13x9-inch baking pan with cooking spray.
In a large bowl beat butter with an electric mixer on medium 30 seconds. Add granulated sugar, baking powder, and salt.
Beat until fluffy. Beat in 2 whole eggs, the 2 egg yolks and 1 tsp. vanilla until smooth.
Beat flour into butter mixture on low until just combined.
Transfer mixture to prepared pan and spread to an even layer. Top with chocolate chips, mini marshmallows, and pecans.
Beat the remaining 2 egg whites on high until stiff peaks form, about 2 minutes.
Fold in brown sugar and remaining 1/2 tsp. vanilla until combined and there are no lumps. Spread on top of chocolate chip layer.
Bake 20 minutes or until top is golden brown. Let cool completely on a wire rack before cutting into squares.