Preheat the oven to 350° F. Line an 8-by-8-inch baking pan with aluminum foil and spray with cooking spray. Set aside.

Cream together the butter, sugar, and peanut butter in the bowl of an electric mixer until smooth and creamy. Add the egg, brown sugar, vanilla, and mix until smooth. Add the flour and baking soda and stir until just combined, don’t overmix.

Stir in chocolate chips and Reese's Peanut Butter Chips, saving some to top the bars with at the end.

Spread about half of the batter out into the prepared pan, smoothing the top lightly with a spatula. Spread the Nutella over the batter. Spread the other half of the batter on top of the Nutella layer.

Bake for about 20 to 25 minutes or the edges of the bar look golden brown or until a toothpick inserted in the center should come out clean. Sprinkle the top of the bars with the remaining chocolate chips and Reese's Peanut Butter Chips. Allow bars to cool in the pan for at least 30 minutes before slicing and serving.