1 Preheat oven to 325°F. For the Streusel Topping, mix flour, brown sugar and cinnamon in medium bowl. Cut in cold butter with pastry blender or 2 knives until mixture resembles coarse crumbs. Stir in pecans. Set aside.
2 For the Cake, beat softened butter, granulated sugar and sour cream in large bowl with electric mixer on medium speed until light and fluffy. Add eggs, 1 at a time, beating well after each addition. Mix in vanilla. Gradually beat in flour and baking soda on low speed until well mixed.
3 Spoon 1/2 of the Streusel Topping into greased and floured 12-cup Bundt pan. Spoon 1/2 of the batter over top. Repeat layers.
4 Bake 1 hour or until toothpick inserted in center comes out clean. Cool in pan 10 minutes. Remove from pan. Cool completely on wire rack. Sprinkle with confectioners' sugar, if desired.