1 stick butter (8 tablespoons sliced into 1/2 inch pieces and softened)
1 1/2 teaspoons baking powder
1/2 teaspoons baking soda
3/4 cup sour cream
1 large egg
1 Teaspoon vanilla
Preheat oven to 350F.
Finely chop the nuts or run them though s food processor to about the size you would use to sprinkle on ice cream. In a medium size, bowl mix together the nuts, cinnamon and brown sugar.
In a large bowl whisk together the flour, granulated sugar, and salt. Distribute the butter slices evenly over the top of the flour mixture and work it in with a fork until the butter is about the size of rolled oats. (You can use a food processor for this step – I use my fingers and it works great) remove 1/ 2 cup of the flour mixture and work it into the brown sugar mixture using a fork to create the streusel.
Remove 3/4 cup of the streusel and set aside.
in a small bowl whisk together the eggs, sour cream and vanilla. Mix the baking soda and baking powder into the flour mixture and then mix in the sour cream mixture just until moistened. (Batter will look crumbly) and then fold in the ¾ cup of the streusel.
Using a large spoon divide the batter between 12 regular muffin cups lightly sprayed with cooking spray, or 6 jumbo muffin cups; divide and sprinkle the remaining streusel over the top pressing lightly to incorporate the streusel into the muffins.
Bake for 18-20 minutes or until a toothpick comes out with just a couple of crumbs attached to it. (For jumbos baking time will almost double)
After a couple of minutes remove the muffing to a cooling rack and serve warm.
Tip: These reheat really nice in the microwave topped with butter.