1. Heat oven to 350 degrees F. Butter and flour a 9 or 10-inch springform baking pan. 2. Sift flour, baking powder, and salt together in a medium bowl. 3. In a separate large bowl cream butter and sugar together until light and fluffy, about 3 minutes on medium speed. On low speed add eggs and vanilla, beating until fully incorporated 4. Add 1/4 of flour mixture, alternating with milk, beating each addition until fully incorporated, starting and ending with the flour mixture. Gently fold in blueberries. Batter will be thick. Make the streusel topping.