Unsalted butter at room temperature 2 tbsp
All purpose flour 3 tbsp
Firmly packed brown sugar 1/3 cup
Chopped walnuts 3/4 cup
Ground cinnamon 1 1/2 tbsp
For the batter
All purpose flour 2 1/2 cups
Baking powder 2 tsp
Baking soda 1/2 tsp
Unsalted butter at room temperature 3/4 cup
Granulated sugar 1 1/4 cups
Large eggs 4
Vanilla extract 1 tsp
Sour cream 1 1/2 cups.
Position rack in the middle of the oven and preheat to 350˚F. Butter and flour a 10 inch tube pan or bundt pan.
To make the streusel filling, in a small bowl combine the butter, flour, brown sugar, walnuts and cinnamon. Mix with a fork until crumbly. Set aside.
To make the batter.
In a bowl stir together the flour, baking powder, baking soda and salt. Set aside.
In a large bowl beat togheter the butter and granulated sugar on medium low speed until creamy . Beat in eggs one at the time.
Stir in the vanilla.
Add the dry ingredients alternating with the sour cream. Start and end with the dry ingredients. Take care to scrap the bowl after each addition. Mix on low speed just until batter is blended and almost smooth.
Pour half of the batter into the prepared pan and smooth with a rubber spatula. Sprinkle evenly with the streusel filling.
Then pour the last half of the batter and smooth it over.
Bake in the preheated oven for 50 to 60 minutes or until the toothpick comes out clean.
TIP: try using a mixture of 2 tbsp of fine granulated sugar and 1 tsp of ground cinnamon to sprinkle on the buttered pan instead of flour. You will use about 3/4 of the mixture and use the rest to sprinkle over the top of the batter after you poured it in the pan.