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Pumpkin Bars With Brown Sugar Frosting

Pumpkin bars with brown sugar frosting: tender pumpkin cake bars baked in a greased 15x10 pan and finished with a rich, swirled brown sugar buttercream. The frosting is cooked to caramelize, then cooled until spreadable and sets as it firms.
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Prep Time 20 minutes
Cook Time 30 minutes
Total Time 50 minutes
Servings: 24 bars
Course: Dessert
Cuisine: American
Calories: 340
Ingredients Equipment Method Notes

Ingredients
  

For the bars
  • 2 cup flour
  • 2 tsp baking powder
  • 0.5 tsp baking soda
  • 2 tsp pumpkin pie spice
  • 1.5 tsp cinnamon
  • 0.5 tsp salt
  • 4 eggs
  • 1.67 cup sugar Use 1 2/3 cups.
  • 1 cup oil
  • 1 can (15 oz) pumpkin
  • 1 tsp vanilla
For brown sugar frosting
  • 0.5 cup unsalted butter
  • 1 cup brown sugar Packed.
  • 0.33 cup heavy cream
  • 2.5 cup powdered sugar
  • 1 tsp vanilla
  • 0.5 tsp cinnamon
  • 0.25 tsp salt Pinch.

Equipment

  • 1 sheet pan

Method
 

Bake the pumpkin bars
  1. Preheat the oven to 350F, then grease a 15x10 pan. The surface should be lightly coated so the bars release cleanly.
  2. Whisk together the flour, baking powder, baking soda, pumpkin pie spice, cinnamon, and salt in a mixing bowl. Whisk until the spices are evenly distributed.
  3. Beat the eggs, sugar, oil, pumpkin, and vanilla until smooth. Stop when the batter looks glossy and well combined.
  4. Fold the wet ingredients into the dry ingredients, then spread the batter evenly in the prepared pan. Use a spatula to level the top for even baking.
  5. Bake for 25-30 minutes at 350F, until the center looks set and a toothpick comes out mostly clean. Let the bars cool completely in the pan before frosting.
Make and spread brown sugar frosting
  1. Melt the butter and brown sugar together over medium heat, and cook for 2 minutes. Stir until thickened and glossy.
  2. Add the heavy cream and bring back to a boil, then remove from heat and cool for 15 minutes. The mixture should be warm but no longer actively boiling.
  3. Beat in the powdered sugar, vanilla, cinnamon, and salt until smooth and fluffy. Mix until the frosting holds its shape and spreads easily.
  4. Spread the frosting immediately over the cooled bars. Let it firm as it cools for clean, sliceable rectangles.

Notes

For the smoothest frosting, cool the brown sugar mixture exactly 15 minutes before beating—too hot can make it loose, and too cool can cause graininess. Store bars airtight in the fridge up to 4 days; freeze unfrosted or frosted for up to 2 months (thaw in the fridge overnight) for best texture. For a lighter option, you can use half oil and half unsweetened applesauce in the bars without changing bake time.