chopped chocolate or real chocolate sprinkles, for garnish
Preheat oven to 325 degrees. In a mixing using a fork, blend together crushed Oreos and butter.
Divide mixture evenly among 12 paper lined standard size muffin cups, adding a heaping 1 Tbsp to each. Press crumbs into an even layer.
Bake in preheated oven 5 minutes. Remove from oven and allow to cool while preparing filling.
In a mixing bowl whisk together granulated sugar and flour. Add in cream cheese and using an electric hand mixer, whip just until smooth. Blend in eggs.
Add in milk, sour cream and vanilla and mix just until combined, then add in Nutella and mix just until combined. Tap bowl forcefully against countertop about 30 times to release some of the air bubbles.
Divide mixture among muffin cups, pouring over crusts and filling each cup nearly full, about 1/4 cup batter in each. Bake in 325 degree oven 20 - 24 minutes until centers only jiggle slightly.
Remove from oven and allow to cool at room temperature 30 minutes, then cover loosely with plastic wrap or foil and transfer to refrigerator and chill 3 hours.
Serve with sweetened whipped cream, hazelnuts, chopped chocolate or chocolate sprinkles (for best results add toppings within a few hours of serving).
Store in refrigerator in an airtight container.
*Don't use Double Stuf Oreos (there would be too much filling and the crusts would likely be too soft. To crush the Oreos I just used a food processor, but you could also just place them in a large resealable bag and finely crush with a rolling pin.