Heat oven to 400°F. Grease large cookie sheet. Combine oats and sugar. For streusel topping, combine 1/4 cup oat mixture and 1 tablespoon of melted margarine in small bowl; set aside. For muffins, add flour, baking powder and ginger to remaining oat mixture; mix well. Add combined milk, remaining melted margarine and egg; mix just until dry ingredients are moistened. Stir in blueberries. For each muffin top, drop batter by 1/4 measuring cupfuls onto prepared cookie sheet. Sprinkle streusel topping evenly over batter, patting gently. Bake 20 to 22 minutes or until golden brown. Serve warm.