Preheat the oven to 350°F (175°C) and grease and flour a 9-inch Bundt pan.
In a large bowl, beat together the sugar and butter using an electric mixer until light and fluffy. Add eggs, one at a time, mixing well after each addition. Stir in sour cream and vanilla extract.
In a separate bowl, combine the flour, baking powder, and salt. Gradually add this dry mixture to the wet ingredients, stirring until just blended. Fold in the blueberries gently.
Spoon half of the batter into the prepared Bundt pan. In a small bowl, mix the brown sugar, chopped pecans, and cinnamon. Sprinkle half of this mixture over the batter.
Top with the remaining batter, followed by the rest of the brown sugar and pecan mixture. Use a knife or thin spatula to swirl the sugar mixture into the cake.
Bake in the preheated oven for 1 to 1¼ hours, or until a toothpick inserted into the center comes out clean.
Let the cake cool briefly in the pan before inverting onto a serving plate. Dust with confectioners' sugar before serving.
Cook’s Tip:
If using frozen blueberries, the baking time may be slightly longer.