Preheat your oven to 350°F (175°C). This ensures your cake bakes evenly.
Grease your Bundt pan thoroughly with butter or non-stick spray. This will help prevent the cake from sticking.
In a large mixing bowl, combine the softened butter and 1 ½ cups of white sugar. Using an electric mixer, beat them together until light and fluffy, about 3-5 minutes.
Add the eggs one at a time, ensuring each egg is fully incorporated before adding the next. Then, mix in the vanilla extract.
In a separate bowl, whisk together the all-purpose flour, baking powder, baking soda, salt, and ground cinnamon.
Gradually add the dry ingredients to the creamed mixture, alternating with sour cream. Begin and end with the flour mixture. Mix each addition until just combined.
Gently fold in the chopped walnuts, being careful not to overmix.
Pour the batter into the prepared Bundt pan, smoothing the top with a spatula.
Bake in the preheated oven for 50 to 60 minutes, or until a toothpick inserted in the center comes out clean.
Once baked, remove the cake from the oven and let it cool in the pan for about 10 minutes. Then, invert it onto a cooling rack to cool completely. Serve plain or with a light glaze if desired.