Butterscotch Marshmallow Squares with Browned Butter Icing

1/4 cup butter
1 cup brown sugar
1 egg
1 teaspoon vanilla extract
1 cup sifted all-purpose flour
1/2 teaspoon salt
1/2 teaspoon baking powder
1/2 cup chopped nuts
2 cups miniature marshmallows

Cream butter, brown sugar and egg; add vanilla extract and beat well.

Sift together flour, salt and baking powder and stir into creamed mixture. Add chopped nuts.

Bake in 8-inch square pan at 350 degrees F for 30 minutes or until golden brown. Remove from oven and top with marshmallows. Return to oven to brown for 2 minutes. Cool thoroughly before icing.

Browned Butter Icing:
1/4 cup butter
1 tablespoon all-purpose flour
Pinch of salt
1 1/2 cups sifted confectioners' sugar
1/4 teaspoon vanilla extract
1/4 cup milk

Heat butter in saucepan over medium heat. Heat until delicately brown. Remove from heat and blend in flour and salt. Slowly stir in milk. Return to moderate heat and cook until boiling, stirring constantly. Boil for one minute. Remove from heat and stir in confectioners' sugar and vanilla extract. Stir rapidly until thick enough to spread over cold marshmallow layer.