Preheat the oven to 375F. Grease and flour a tube cake pan.
Cream butter and sugar in a stand mixer. Add the eggs and then the sour cream, continuing to blend.
Add the vanilla, stirring until smooth, about 2-3 minutes.
Sift all of the dry ingredients into a bowl together. Add the dry ingredients to the blending wet ingredients and mix, starting slowly so the flour doesn’t puff everywhere. Mix until all of the dry ingredients are incorporated. Make the filling as the batter is mixing.
Once the batter is done, spoon 1/2 of the batter into the prepared tube pan. Put 1/2 (or a little more) of the filling on top of the batter, making sure the whole cake batter is covered with filling.
Pour the rest of the batter on top of the filling and then top with the remaining filling.
Bake at 375F for 35-40 minutes, until a cake tester comes out clean. When done, cool in a pan for 20 minutes, then remove the cake and the center tube part of the pan and let cool for another 10 minutes.
Remove the cake from the center tube and place on a dish to serve and enjoy!
Filling
Combine the sugar, cinnamon, nutmeg, and chopped walnuts. It’s easiest to either buy the nuts chopped or blend them in a food processor. Set aside.