I have a recipe for Banana Fudge-Walnut Brownies. They're yummy
(hazel can't stop eatin' 'em so she doesn't make 'em often any more 
), are easy to make, don't need refrigeration for the amount of time you'll need, can be eaten with the fingers with minimal mess, and did I say they're yummy?
The only hitch is one batch makes only 16 small (2in x 2in) brownies, so if you're feeding a lot of people, you'll need more than one batch.
BANANA FUDGE-WALNUT BROWNIES
Heat oven to 350 degrees. Grease bottom only of 8-inch square pan.
Combine in a small bowl or measuring cup:
3/4 c all-purpose flour
1/4 teaspoon baking powder
1/4 teaspoon salt
Melt in a 2-quart saucepan over low heat, stirring constantly:
1/4 c (1/2 stick) margarine or butter
1 6-oz package (1 c) semisweet chocolate chips
Beat in thoroughly with spoon:
1/2 c sugar
1/2 teaspoon vanilla
1 egg
1/3 - 3/4 c mashed banana (1 to 3 small bananas--the more you add, the moister they'll be)
the flour mix from above
1/3 - 1/2 c walnut pieces (or chopped walnuts)
Spread batter evenly in pan.
Bake about 30 minutes or until center is set; cool completely. Cut into 2-inch squares. Dust with powdered sugar.
Whew! had to type that in twice cuz hazel's connection quit mid submission the first time! 