Nancy's Brown Sugar Nut Bars

My Mother orginally found these in Farm Journal. I'm not sure how long ago but possibly in the 70's. These are one of my favorites made for birthdays and holidays, simple but full of flavor!Hope you enjoy.

• Ready In: 40 mins
• Serves: 35

Ingredients

• For the bars

• 1 (16 ounce) box light brown sugar
• 1  cup butter (2 sticks)
• 2  large eggs
• 2  cups  sifted flour
• 1  teaspoon baking powder
• 1⁄2 teaspoon salt
• 1  cup  coarsely chopped pecans or 1  cup walnuts

• For the Icing

• 1  tablespoon water
• 1  cup powdered sugar
• 2  tablespoons mayonnaise (She uses Hellman's)
• 1  teaspoon vanilla

Directions

1. Preheat oven to 350°.
2. Cook sugar and butter in top of double boiler over hot water until sugar dissolves.(My mother uses a 3-quart heavy pot without the double boiler).
3. Let Cool.
4. Add eggs, one at a time, beating thoroughly after each addition.
5. Stir in remaining ingredients.
6. Spread in an ungreased 15 x 10 x 1-inch jelly-roll pan.
7. Bake at 350° for 25 minutes (she usually cooks 22 minutes).
8. While hot cut into 2-inch squares.
9. Cool in pan on rack.
10. Frost: Icing recipe below if desired--*It's also good on other bars as well*.
11. Mix frosting ingredients together in a small bowl until creamy. (It is supposed to be thin).