Preheat oven to 350°F. Line a muffin pan with 7 grease-proof liners.
In a medium bowl, combine streusel topping ingredients, blending together until combined and only pea size chunks remain.
In a small bowl, combine brown sugar and cinnamon to create the filling.
In the bowl of a stand mixer, or large bowl, beat butter until smooth. Cream together butter and sugars, followed by egg and vanilla. Mix until combined. Scrape sides of bowl as needed. Add the cinnamon, salt, baking powder, baking soda and half of the flour, mixing until combined. Add sour cream, followed by remaining flour. Continue mixing only until no streaks remain and batter is well combined.
Add 1 medium scoop, or roughly 1/3 full, to each liner. Sprinkle cinnamon-brown sugar mixture onto the center of each scoop of batter. Add an additional medium scoop to each liner, or 2/3 full. Top off with a general spoonful of streusel topping.
Bake for 18-22 minutes or until a toothpick inserted comes out clean. Cool in pan for several minutes before removing to a wire rack to cool completely.
Nutritional information is provided as a courtesy and is an estimate only. Nutrition information can vary for a variety of reasons. For the most accurate data, use your preferred nutrition calculator with the actual ingredients you used to make this recipe.
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