1Heat oven to 400°F. Spray 10 heart-shaped or regular muffin cups with nonstick cooking spray. In medium bowl, combine flour, brown sugar, baking powder, baking soda and salt; mix well.
2In small bowl, combine yogurt, margarine and egg; blend well. Add to dry ingredients; stir just until dry ingredients are moistened. Gently stir in frozen raspberries. Fill each sprayed muffin cup with about 1/4 cup batter.
3In another small bowl, combine sugar and cinnamon; mix well. Sprinkle 1/4 teaspoon mixture over batter in each cup.
4Bake at 400°F. until tops are golden brown and toothpick inserted in center comes out clean. Bake heart-shaped muffins 12 to 16 minutes; bake regular muffins 14 to 18 minutes. Cool 1 minute; remove from muffin cups. Serve warm.