Spray a 11.5x17-inch pan with non-stick baking spray.
Line the bottom of the pan with parchment paper, then spray the surface of the paper with more baking spray.
Bake the Cake:
Preheat the oven to 350°F.
Sift together the dry ingredients in a bowl. Whisk them to make sure they are well mixed.
2 cups all purpose flour, 2 teaspoons baking powder, 1 teaspoon baking soda, 1 teaspoon salt, 2 teaspoons cinnamon, ½ teaspoon ground cloves, ½ teaspoon ground ginger, ½ teaspoon ground nutmeg
In a separate bowl, add the wet ingredients. Whisk to combine.
15 ounces pumpkin purée, 1⅔ cups sugar, 1 cup vegetable oil, 4 large eggs
Fold the dry ingredients into the wet ingredients.
Evenly spread the batter into the prepared pan.
Bake the cake until it is cooked through and a toothpick comes out clean, about 20 minutes. Allow cake to cool completely before frosting.
Make the Frosting:
Beat the butter and cream cheese together on medium-high speed in the bowl of an electric mixer fitted with the whisk attachment.
6 tablespoons butter, 3 ounces cream cheese
Reduce the speed to low and add the cream and vanilla extract.
1 tablespoon cream or milk, 1 teaspoon vanilla extract
Slowly add the powdered sugar by the spoonful until all has been added. Turn the mixer up to medium-high speed and beat for 4 minutes until frosting is light and fluffy.
1¾ cups powdered sugar
Frost and Cut the Cake:
Add the frosting to the top of the cake. Use an offset icing spatula to smooth the frosting in an even layer over the surface of the cake.
Slice the cake into 24 squares, or more if you prefer smaller pieces.
Notes
Source: Adapted from recipes by family friend Jeanette A. and AllrecipesYou're Gonna Bake It After Allbakeitafterall.com