– Preheat oven to 400 degrees. Add liners to a muffin tin and set aside. – In a large bowl, vigorously whisk eggs and brown sugar until light and thick. – Slowly stream oil into the bowl, whisking continuously until combined. – Add Greek yogurt, vanilla and buttermilk. Whisk until incorporated. – In a separate bowl sift together dry ingredients. – Toss in chocolate chips and stir to coat with flour mixture.

– Gradually add dry ingredients to wet. Stir until just combined. – Fill muffins liners 3/4 of the way full.  – Swirl 2 teaspoons of Nutella on top. – Bake for 5 minutes at 400 degrees then lower the temperature to 350 and bake for an additional 10 to 12 minutes or until a toothpick inserted in the center comes out with a few moist crumbs. – Transfer muffin tin to a wire rack to cool for 5 minutes before removing muffins to cool completely.