1cupbutter melted and then cooled for at least 5 minutes
1cuplight brown sugartightly packed
3/4cupsugar
2eggs + 1 egg yolkroom temperature preferred
1 ½teaspoonvanilla extract
2 1/2cupsall purpose flour
2teaspoonscornstarch
1 /2teaspoonbaking powder
1teaspoonsalt
1/2cupNutella
Instructions
Preheat oven to 350F and prepare a 9x13 baking pan by lining with parchment paper.
Combine melted (cooled) butter and sugars in a large bowl, stir well.
Add eggs, and egg yolk one at a time, stirring well after each addition.
Stir in vanilla extract.
In a separate, medium-sized bowl, whisk together flour, cornstarch, baking powder, and salt.
Gradually stir dry ingredients into wet until completely combined.
Spread batter evenly into prepared pan and then drop your Nutella by spoonfuls over the batter. Use a butterknife to swirl the Nutella through the batter.
Transfer to the oven and bake on 350F for 25 minutes or until edges just begin to turn golden brown and a toothpick inserted in the center comes out clean.