Preheat the oven to 425 degrees F.
Spray the pan with cooking spray in the event that the muffins spread too much.
Place 16 paper liners in muffin pans. These muffins will be quite large.
In the bowl of an electric mixer fitted with the paddle attachment, cream the butter and sugar until light and fluffy, about 5 minutes.
With the mixer on low speed, add the eggs 1 at a time, then add the vanilla, yogurt, sour cream, and milk.
Sift together the flour, baking powder, baking soda, and salt.
*one trick I learned was to sift all the dry ingredients on a piece of parchment paper. That way the parchment paper can be folded up and easily poured into the mixing bowl without making a mess.
With the mixer on low speed add the flour mixture to the batter and beat until just mixed.
Combine all the ingredients for the cream cheese filling in a standing mixer and set aside. It will be on the liquid side, do not worry.
Place the Nutella into the microwave for a minute to make it more liquid and pour into squirt bottle. (HINT: Keep bottle warm submerged in a bowl of hot water so the Nutella does not harden.)
Take the Nutella and squirt it on the bottom of the muffin cups as well as on the side. It does not have to look neat. Be generous with it.
Scoop the muffin batter into the prepared muffin pans just one third of the way up with an ice cream scoop or spoon. (HINT: Spray your scoop or spoon with pan spray so that the batter does not stick to the scoop)
Take one scoop of the cheesecake filling and scoop on top.
Squirt Nutella onto the cheesecake filling layer.
Repeat these steps once more.
Once you reach the top layer of Nutella, squirt some out onto the top and swirl it through the cheesecake filling layer with a tooth pick.
Place into the oven for 5 minutes at 425-degrees and then drop the temperature to 375. This allows your muffins to rise and get those big and beautiful tops.
Bake for 20-25 minutes or until the muffins a tooth pick comes out clean.
Let rest for 5 minutes before moving to a cooling rack to cool.
Serve with more drizzles of Nutella and powdered sugar.