Preheat the oven to 350˚F. Coat a 9 X 13-inch baking pan with nonstick spray, if desired. OR cover the bottom and sides of the baking pan with aluminum foil.
Cooked the diced bacon in a small non-stick skillet over medium heat until crisp; drain on a paper towel-lined plate and set aside. Reserve 2 tablespoons drippings.
Whisk together flour, baking soda, cinnamon, and salt for the bars in a medium bowl; set aside.
Whisk together pumpkin puree, granulated sugar, 1/2 cup brown sugar, the egg, melted butter, bacon drippings and vanilla in a large until well blended. Stir in the flour mixture and pecans and blend thoroughly with the wet ingredients.
Spread the pumpkin batter evenly into the prepared pan. bake until a toothpick inserted into the center comes out clean, about 20-25 minutes. Let cool completely before frosting.
Caramel Frosting
Boil 2 cups brown sugar, water and a pinch of salt for the frosting in a large saucepan over high heat, 5 minutes, swirling occasionally to prevent scorching. Whisk in the cream and butter pieces. (NOTE: Mixture will bubble furiously.) Keep whisking. Boil 2 minutes more.
Transfer caramel frosting to the bowl of a stand mixer. Whip on high speed until the sides of the bowl are cool to the touch and the caramel is thick, about 10 -minutes, scraping down the sides of the bowl with a rubber spatula. Add the cream cheese, 1 cube at a time, until the frosting is smooth.
Carefully pull back the foil from the sides of the pumpkin cake. Using a cake spatula, spread the frosting over the cooled cake.
Sprinkle the reserved cooked bacon over the frosted cake. If desired, sprinkle with additional chopped pecans. prinkle with sea salt.
With a sharp knife, cut the cake into 24 bars and serve.