====== Cinnamon Swirl Bundt Coffee Cake ======
<sub>Preheat oven to 400 degrees</sub>
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==== Ingredients ====
  * 3/4 cup butter, room temperature
  * 1 1/2 cups white sugar
  * 3 eggs
  * 1 teaspoon vanilla extract
  * 1 cup sour cream
  * 2 1/2 cups all-purpose flour
  * 1 teaspoon baking soda
  * 1 teaspoon baking powder
  * 1/2 cup chopped walnuts
  * 1 tablespoon ground cinnamon
  * 1/4 cup white sugar

==== Directions ====
  - Preheat oven to 400 degrees F (205 degrees C). Grease a 10-inch bundt pan.
  - Beat butter and sugar with an electric mixer in a large bowl until light and fluffy. The mixture should be noticeably lighter in color. 
  - Add eggs one at a time, allowing each egg to blend into the butter mixture before adding the next. 
  - Mix in vanilla.
  - Combine flour, baking soda, and baking powder. Pour flour mixture into batter alternately with the sour cream, mixing until just incorporated. 
  - Fold in walnuts, mixing just enough to evenly combine. 
  - Pour half the batter into the prepared pan.
  - Mix the remaining 1/4 cup of white sugar with the cinnamon.
  - Sprinkle cinnamon sugar over the batter in the pan. 
  - Drop remaining cake batter in heaping spoonfuls over filling, covering it as best you can.
  - Bake in preheated oven for 8 minutes. 
  - Lower heat to 350 degrees F (175 degrees C) and bake for an additional 40 minutes, or until a tester comes out clean.