Blueberry Buckle

Name: Blueberry Buckle
Ingredients: Cake:; 2 cup Flour; 2 tsp Baking Powder; 1/2 tsp Salt; 3/4 cup Sugar; 1/4 cup Butter; 1 Egg; 1 tsp Vanilla; 1/2 cup Milk; 6 oz fresh Blueberries; Streusel:; 1/3 cup Sugar; 1/3 cup Flour; 1 tsp Cinnamon; 1/8 tsp Salt; 4 tbsp Butter