Preheat the oven to 350F. Butter and flour every nook and cranny of a full sized 12-14 cup non-stick bundt pan.

In a stand mixer (or with electric beaters) cream the butter and brown sugar together until light and fluffy.

Beat in the eggs, one at a time, scraping down the bowl as you go, and then add the vanilla.

Sift or whisk together the dry ingredients.

With the mixer on a medium-low speed, add the dry ingredients to the wet, alternately with the sour cream, beginning and ending with the dry ingredients. Mix with a silicone spoon to ensure everything is well combined.

Toss the nut mixture together with a fork.

Begin layering the cake by adding 1/3 of the batter into the prepared pan. Top with 1/2 of the nut mixture. Add another 1/3 of the batter, then the rest of the nut mixture, and finally top with the remaining batter. Gently spread the batter across the top surface.

Bake for 1 to 1 1/2 hours, using the toothpick test for doneness. If the cake appears to brown too quickly, lay a loose piece of foil over the top.

Let the cake cool on a rack for 10 minutes, then loosen the edges with a flexible spreader and invert onto a plate or cooling rack.