Preheat oven to 450 degrees. Put muffin cups in muffin tin. In large bowl, mix butter and sugar until creamy. Add eggs one at a time until well blended. Gradually add sour cream and flour/baking powder alternating wet and dry.
When just mixed, add vanilla and blueberries. Stir in. Fill muffin cups. Bake for 15-20 minutes until golden on top and toothpick comes out clean. Let rest for 10 minutes and remove from muffin tin. Best served warm.