Preheat oven to 350 degrees F.
Line muffin tin. Do not use cooking spray.
Combine butter and sugar in a mixing bowl. Cream until light and fluffy. Add eggs and vanilla and mix well.
In a separate bowl, combine all dry ingredients. Add half the dry mixture to butter and sugar combination and stir. Add sour cream and buttermilk and mix to combine. Add the remaining half of the dry mixture and mix until batter is smooth.
Use a spoon or scooper to drop rounded balls of batter into the bowl with cinnamon and sugar. Roll the batter carefully in the cinnamon sugar mixture. Put the ball into a muffin liner.
When all muffins are prepared, sprinkle any leftover cinnamon sugar onto the tops of the muffins.
Bake about 15-18 minutes until golden on top.
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