Grind hazelnuts in a food processor until finely ground and beginning to clump together. Add oil and continue to process until well combined, scraping down sides of processor with a rubber spatula as needed.
Add cocoa powder, whipping cream, sweetener and vanilla and process until smooth and creamy. If it is too thick, add additional oil or cream until desired consistency is achieved.
Preheat oven to 325F and line a standard muffin pan with 12 paper liners (I recommend parchment liners).
In a medium bowl, whisk together almond flour, protein powder, baking powder, and salt.
In a large bowl, beat coconut oil or butter with sweetener until smooth.
Beat in eggs, vanilla and stevia, then in almond flour mixture in two additions, alternating with almond milk.
Divide about half the batter evenly among prepared muffin cups. With the back of a spoon, make a well in the center of each.
Spoon about 1 tbsp of sugar-free nutella into each well. Top with remaining muffin batter.
Bake 20 to 22 minutes, or until set and lightly browned on top.
In a small bowl, whisk together sweetener and cinnamon. Brush the tops of hot muffins with melted butter and sprinkle with cinnamon "sugar".
Serves 12. Each serving has 8 g of carbs and 4 g of fiber. Total NET CARBS = 4 g.310 Calories; 29g Fat (77.5% calories from fat); 10g Protein; 8g Carbohydrate; 4g Dietary Fiber; 63mg Cholesterol; 165mg Sodium.