Preheat the oven to 350 degrees. Greased Tube pan (Angel Food Cake Pan)Place one stick of softened butter and 1 cup of white sugar into a large bowl. Beat the two together with an electric mixer until light and fluffy. Add the eggs to the bowl one at a time, beating well after each egg addition. Add the vanilla and beat it into the batter. The next step is to sift the dry ingredients together before we add them to the batter. Place the flour, baking powder, baking soda and salt in a medium bowl. Grab yourself a large bowl. Place the dry ingredients into a sifter and sift them into the larger bowl. We're going to add the sifted dry ingredients to the batter alternately with the sour cream. It's going to look like this: flour , sour cream, flour, sour cream and then the last batch of flour. Always start with an addition of flour and end with an addition of flour. Beat each addition of flour and sour cream into the batter until it's just incorporated as you go. Pour half of that gorgeous ,thick, creamy batter into a greased tube pan also known as an Angel Food Cake Pan. Spread it out into the pan so it's even. It's time to make the topping that goes in the middle and on top of the cake. Place 1 cup chocolate chips, 1/2 cup chopped nuts, 3/4 cup light brown sugar, 2 Tablespoons of softened butter and 1 Tablespoon of cinnamon in a medium size bow. Mix it all together with a spatula or get your fingers in the bowl and rub everything together. Spread half of the topping over the batter in the pan evenly. Place the remaining batter over the filling, then place the remaining topping over the batter. Bake in a preheated 350 degree oven for 40 minutes or until a toothpick inserted in the center comes out clean. Cool on a wire. To get the cake out of the pan run a butter knife around the sides of the pan and remove the outer pan. Run a butter knife around the bottom of the pan and down the sides of the tube in the center to release the cake and invert it onto a serving plate.
For the Topping:
Place the topping ingredients into a medium bowl. Mix all the ingredients together until well blended.