Whisk together 2 eggs and 3/4 cup sugar until light and fluffy, about 4 to 5 minutes.
Mix in 1/2 cup melted butter or vegetable oil and 1 cup milk (full cream or fresh).
Stir in 2 cups all-purpose flour, 1 teaspoon vanilla extract, 2 teaspoons baking powder, and 1/2 teaspoon salt.
Fold the mixture until just combined. Do not overmix.
Gently fold in about 1 cup of chocolate chips (semi-sweet or dark).
Preheat oven to 180 degrees Celsius.
Fill muffin cups three-quarters full with a layer of hazelnut spread, add additional chocolate chips in the middle as desired, and top off with another layer of batter. Add more chocolate chips on top.
Bake for 22 minutes or until golden brown and a toothpick inserted into the center comes out clean.
Let muffins cool before serving.