Preheat the Oven and Prepare the Pan. Preheat your oven to 350°F and generously grease a 10-cup bundt pan with butter or non-stick spray. Dust lightly with flour to ensure the cake releases easily after baking.
Mix Dry Ingredients. In a large bowl, whisk together the flour, baking soda, baking powder, cinnamon, nutmeg, and salt. Set aside.
Cream Butter and Sugars. In another large bowl, beat the unsalted butter with the granulated sugar and brown sugar until light and fluffy, about 2-3 minutes. Add the eggs, one at a time, beating well after each addition.
Add Wet Ingredients. Stir in the pumpkin puree, sour cream, and vanilla extract until fully combined.
Combine Wet and Dry Ingredients. Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Be careful not to overmix, as this can result in a dense cake.
Pour into Bundt Pan. Pour the batter evenly into the prepared bundt pan, smoothing the top with a spatula.
Bake the Cake. Bake for 55-65 minutes, or until a toothpick inserted into the center comes out clean. Let the cake cool in the pan for 15 minutes before transferring it to a wire rack to cool completely.
Prepare the Glaze. In a small bowl, whisk together the powdered sugar and 2-3 tablespoons of milk (or apple cider) until smooth. Drizzle over the cooled cake.
Serve and Enjoy! Slice and serve this delicious pumpkin bundt cake with a cup of coffee, tea, or even a scoop of vanilla ice cream.