Here is the recipe on how to make pumpkin bars:...

What you'll need:
2 cups all-purpose flour
2 teaspoons baking powder
2 teaspoons ground cinnamon
1 teaspoon baking soda
4 beaten eggs
1 16-ounce can pumpkin
1 1/2 cups sugar
1 cup cooking oil
cream cheese frosting (see recipe below)

How To Make Cream Chese Frosting
Ingredients:
1 3-ounce package cream cheese
1/4 cup butter or margarine
1 teaspoon vanilla
2 cups sifted powdered sugar

Here's How:
In a mixer bowl beat together cream cheese, butter or margarine, and vanilla till light and fluffy. Gradually add powdered sugar, beating till smooth. Spread over cooled cake; sprinkle with chopped nuts, if desired. Frost tops or 8- or 9-inch layers. Cover; store in the refrigerator.

Here's How To Make Those Pumpkin Bars:
Stir together flour, baking powder, cinnamon, soda, and 1 teaspoon salt, combine eggs, pumpkin, sugar, and oil; beat till combined. Add dry ingredients; beat till well combined. Spread batter in an ungreased 15x10x1-inch baking pan. Bake in a 350degree oven for 25 to 30 minutes. Cool. Frost with cream cheese frosting. Cut into cars. Makes 36 bars.