Gradually add the melted butter to the flour/sugar mix a little at a time while stirring with a fork until clumps form. You should have a soft and crumbly mix with various sizes of clumps
Break apart the clumps so they are as big or as small as you want them and then set aside until you are ready to put on top of the muffins
Prepare the Cream Cheese Filling
Beat the cream cheese, vanilla and sugar until smooth, set aside
1 ½ cups Cream Cheese, ¼ cup White Sugar, ½ teaspoon Vanilla Extract
Make the Muffins
Preheat oven to 350°F / 180°C and line a muffin pan with muffin cases
In a large bowl, whisk together eggs and sugar
3 Eggs, 1 ½ cups White Sugar
Mix in sour cream, oil and vanilla extract
1 ½ cups Sour Cream, 1 cup Vegetable Oil, 1 teaspoon Vanilla Extract
Add flour, baking powder and salt and keep whisking until lump-free
3 cups All-purpose Flour, 4 ½ teaspoon Baking Powder, ½ teaspoon Salt
Fold in the blueberries, don't worry if they colour the batter a little!
2 cups Blueberries
Fill each muffin case halfway with batter
Spoon a heaped teaspoon of cheesecake mix on top of the batter. Try to keep the cheesecake in the centre of the muffin and avoid spreading out to the sides if you can
Add more batter on top of the cheesecake to fill muffin case almsost all the way to the top (we want them nice and full so they will rise and make those beautiful muffin tops!)
Put a generous sprinkle of crumb topping on top of each muffin
Bake for 18-20 minutes or until a skewer comes out clean