1. Heat oven to 350°F. Grease or line muffin cups (2-1/2 inches in diameter) with paper bake cups. Prepare STREUSEL TOPPING; set aside.
2. Stir together flour, sugar, baking powder and salt in medium bowl. Add banana, milk, chocolate spread, egg and vanilla, stirring until well blended. Stir in chocolate chips and pecans, if desired. Fill muffin cups 3/4 with batter. Sprinkle about 1 teaspoon STREUSEL TOPPING over each muffin cup.
3. Bake 25 to 30 minutes or until top springs back when lightly pressed. Cool 15 minutes; remove from pans to wire rack. Cool completely. About 16 muffins.
STREUSEL TOPPING: Stir together 1/4 cup sugar and 3 tablespoons all-purpose flour in small bowl; cut in 2 tablespoons cold butter or margarine until crumbs form.