1 1/2 cups all-purpose flour
3/4 cup sugar
1/2 teaspoon salt
2 teaspoons baking powder
1/3 cup butter, melted and cooled slightly
1 egg, lightly beaten
2/3 cup milk
1 1/2 cups fresh blueberries (about 1 pint)
For the streusel topping
1/2 cup sugar
1/4 cup all-purpose flour
1/4 cup butter, cubed
2 teaspoons ground cinnamon
Preheat oven to 400F. Grease muffin cups or line with muffin liners.
Combine flour, sugar, salt and baking powder in one bowl. In another small bowl, combine melted butter, milk and egg. Mix this with flour mixture. Fold in blueberries. Fill muffin cups right to the top, and sprinkle with crumb topping mixture.
To make streusel topping: Mix together sugar, flour, butter, and cinnamon. Mix with fork until it looks like coarse sand. Sprinkle over muffins before baking.
Bake for 20 to 25 minutes in the preheated oven, or until a toothpick come out clean and they are a golden brown.