1Heat oven to 400°F. Grease bottoms only of 12 regular-size muffin cups with shortening or cooking spray, or place paper baking cup in each muffin cup.
2In small bowl, mix 1/4 cup flour, the brown sugar and cinnamon. Cut in 2 tablespoons cold butter, using pastry blender (or pulling knives through ingredients in opposite directions), until crumbly. Set aside.
3In large bowl, beat milk, melted butter and egg with fork or whisk until well mixed. Stir in 1 1/2 cups flour, the granulated sugar, baking powder and salt all at once just until flour is moistened (batter will be lumpy). Fold in blueberries. Divide batter evenly among muffin cups; sprinkle each with streusel.
4Bake 20 to 25 minutes or until toothpick inserted in center comes out clean. If baked in greased pan, let stand about 5 minutes in pan, then remove from pan to cooling rack; if baked in paper baking cups, immediately remove from pan to cooling rack. Serve warm if desired.