I’m not sure how to adapt a recipe to make it less fluffy and more dense and chewy.
For example, this is one recipe:

Pumpkin Spice Bars
4 Large Eggs
2 Cups Sugar
1 Cup Vegetable Oil
1 can (15 ounces) Pumpkin (not pumpkin pie mix)
2 Cups All-Purpose Flour
2 Teaspoons Baking Powder
2 Teaspoons Ground Cinnamon
! Teaspoon Baking Soda
1/2 Teaspoon Salt
1/2 Teaspoon Ground Ginger
1/4 Teaspoon Ground Cloves
1 Cup Raisins, if desired
1/2 cup Chopped Walnuts, if desired

1. Heat oven to 350°F. Lightly grease bottom and sides of 15x10x1-inch pan with shortening. In large bowl, beat eggs, granulated sugar, oil and pumpkin until smooth. Stir in flour, baking powder, cinnamon, baking soda, salt, ginger and cloves. Stir in raisins. Spread in pan.
2. Bake 25 to 30 minutes or until light brown. Cool completely in pan on cooling rack, about 2 hours.
3. In medium bowl, beat cream cheese, butter and vanilla with electric mixer on low speed until smooth. Gradually beat in powdered sugar, 1 cup at a time, on low speed until smooth and spreadable. Spread frosting over bars. Sprinkle with walnuts.
Or another:

1 cup all-purpose flour
1 teaspoon pumpkin pie spice
1/2 teaspoon baking powder
1/2 teaspoon baking soda
1/2 cup vegetable oil
1 cup white sugar
2 eggs
1 cup solid pack pumpkin puree
3/4 cup raisins

DIRECTIONS:
1. Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 9x13 inch baking pan.
2. In a medium bowl, stir together the flour, pumpkin pie spice, baking powder, and baking soda; set aside. In a large bowl beat the eggs, oil and sugar together until smooth. Stir in the pumpkin, then the dry ingredients. Finally, stir in the raisins.
3. Pour the mixture into the prepared baking pan and spread evenly. Bake for 30 to 40 minutes in the preheated oven. Allow bars to cool before adding the glaze.

If someone can tell me how to adapt this or has a better one, please post.

Thanks!

Ooey Gooey Pumpkin Bars
Makes 6-8 servings

Cake:
1 (18 1/4-ounce) package yellow cake mix
1 egg
8 tablespoons butter, melted

Filling:
1 (8-ounce) package cream cheese, softened
1 (15-ounce) can pumpkin
3 eggs
1 teaspoon vanilla
8 tablespoons butter, melted
1 (16-ounce) box powdered sugar
1 teaspoon cinnamon
1 teaspoon nutmeg

fresh whipped cream, for serving

1. Preheat oven to 350 degrees F.

2. Combine the cake mix, egg, and butter and mix well with an electric mixer. Pat the mixture into the bottom of a lightly greased 13 by 9-inch baking pan.

3. To make the filling: In a large bowl, beat the cream cheese and pumpkin until smooth. Add the eggs, vanilla, and butter, and beat together. Next, add the powdered sugar, cinnamon, nutmeg, and mix well. Spread pumpkin mixture over cake batter and bake for 40 to 50 minutes. Make sure not to overbake as the center should be a little gooey. Serve with fresh whipped cream