Blueberry Overload Coffee Cake Recipe

Have all ingredients at room temperature. Preheat oven to 350u0b0F with a rack in the center, and grease a 9 x 13 x 2-inch baking pan. In a large bowl, stir together the 2 cups flour, baking powder, baking soda, and 1/2 teaspoon salt. In a small bowl, stir together the sour cream and vanilla extract. In another large bowl, beat together the 4 tablespoons butter and the 1 cup sugar until lightened in color and texture, about 3 minutes. Add the eggs one at a time, beating to incorporate after each addition. Then add the flour mixture in three parts, alternating with the sour cream in two parts and beating on low after each addition until just incorporated. Toss the blueberries with the remaining tablespoon of flour and gently fold into the batter. Scrape the batter evenly into the prepared pan.
To make the streusel topping, stir together the flour, brown sugar, nuts, cinnamon and salt in a small bowl. Pour the melted butter overtop and stir to incorporate evenly into the dry ingredients. Use your fingers to sprinkle the topping over the batter. Bake until a cake tester inserted in the middle of the cake comes out almost clean, 30 to 35 minutes. Cool in the pan for a few minutes before serving warm or at room temperature.