I also do not have a jelly roll pan so what I ended up doing was a small layer in a 13 x 9 baking metal sheet/pan I got from pillsbury a little bigger layer in a 13 x 9 glass cake pan and same size layer in a 9 x 9 glass pan. Seriously it makes that much lol. I'm sure you could modify this recipe in half and use a 13 x 9 pan if you do not want that many bars. Also if you do a smaller layer or a metal pan I'd advise only 20 minutes in the oven. I set the timer for 20minutes and took the metal pan out and then left the 2 glass ones in for 10-15 additonal minutes.
1 1/2 cup oil (I used canola)
3 cups sugar
1 1/2 tsp vanilla
1 large can (29 oz) pumpkin (or 2 15oz cans)
3 1/4 cup flour
1 1/2 tsp. baking soda
1 Tbsp cinnamon
1 1/2 tsp. salt
(chocolate chips or cream cheese frosting or both in my case)
Mix together eggs, oil, sugar, vanilla, and pumpkin. Fold in dry ingredients and pour into jelly roll pan (13 x 18 pan) . At this point sprinkle the pan with chocolate chips and/or nuts if desired. Bake at 350 for 30 to 40 minutes until a toothpick inserted in the center comes out clean. Do not over bake. Frost with cream cheese frosting.