Preheat the oven to 350 degrees. Grease and flour a 9” Bundt pan. In a large bowl cream butter and sugar until light and fluffy. Beat in the eggs, one at a time, then stir in the sour cream and vanilla extract. In a separate bowl combine flour, baking powder, and salt. Stir into the wet batter and mix until just blended. Fold in blueberries.
Spoon half of the batter into the greased Bundt pan. In a small bowl combine brown sugar, cinnamon, and pecans. Sprinkle half of this mixture over the batter in the pan. Spoon the remaining batter over the top, and then sprinkle the remaining pecan mixture over the rest of the batter. Use a knife or spatula to swirl the sugar layer into the cake.
Place into the oven and bake for 55 to 60 minutes or until a knife inserted into the cake comes out clean. Remove from the oven and allow to cool on a wire rack. Remove from the pan and dust with confectioner’s sugar.