Maple Walnut Muffins

2 cups flour
1/2 cup brown sugar
2 teaspoons baking powder
1/2 teaspoon salt
1/3 cup melted butter
1 egg
1 cup plain yogurt
1/2 cup maple syrup
1/2 cup coarsely chopped walnuts

Topping:
3 tablespoons flour
3 tablespoons brown sugar
2 tablespoons chopped walnuts
1/2 teaspoon cinnamon
2 tablespoons cold butter

In a large bowl, combine flour, brown sugar, baking powder and salt.

In another bowl, combine melted butter, egg, yogurt, and maple syrup. Pour over the dry ingredients and stir until just moistened. Stir in walnuts.

Pour into greased or paper lined muffin cups.

Topping:
Combine all ingredients in blender or food processor and whirl until crumbly. Sprinkle topping over muffins. Bake at 400 degrees F. for 16 - 20 minutes.