brown butter pumpkin bars with caramelized white chocolate mascarpone buttercream

how’s THAT for a title?! i could just as easily have said, “take everything you love about fall desserts and turn it into the ultimate fall treat.” it really would have been just as accurate. although, just as long of a title! so…..

ok, what makes THIS recipe special? its the layers and layers of flavor. pumpkin spice, browned butter, brown sugar, white chocolate that’s been slow roasted to this caramelized perfection, lush mascarpone and toasted walnuts. im literally drooling while typing this. its not often i go back for thirds, fourths, ok….. half the sheet pan’s worth before “deciding” the recipe was perfect. what can i say? i take quality control very seriously. oh, and its quite possibly the most delicious thing to have ever been created in my kitchen.

this also happens to be the most highly anticipated recipe (most requested on my Instagram) before even hitting the blog. its so, so good. i even made a video! so now i can not stop watching the dessert i can not stop eating! love it. enjoy, friends. -megs

brown butter pumpkin bars with caramelized white chocolate mascarpone buttercream

the title pretty much sums it all up! browned butter pumpkin bars spiced with a healthy dose of pumpkin spice gets topped with a caramelized white chocolate mascarpone buttercream. lightly toasted walnuts complete this "if fall was a dessert" dessert.
Prep Time1 hr 20 mins
Cook Time35 mins
Cooling Time35 mins
Total Time2 hrs 30 mins
Course: Celebrations, Dessert
Cuisine: American
Keyword: caramelized white chocolate, celebration, mascarpone, sheet cake, spiced
Servings: 24

Equipment

  • stand mixer with paddle attachment
  • 9X13 baking pan
  • parchment paper
  • baking sheet

Ingredients

brown butter pumpkin bars

  • 2 c all purpose flour (240g)
  • 1 tsp baking soda
  • 1 tsp baking powder
  • 1 tbsp pumpkin pie spice (see notes)
  • 1/2 tsp salt
  • 1 c unsalted butter (227g), browned and cooled to room temperature (170g) (see notes)
  • 1 c packed light brown sugar (220g)
  • 1/4 c sugar (50g)
  • 3 large eggs, room temperature
  • 1 c pumpkin puree

caramelized white chocolate mascarpone buttercream + toasted walnuts

  • 6 oz. caramelized white chooclate (150g) (see notes)
  • 1 c unsalted butter, softened (113g)
  • 8 oz. mascarpone cheese, room temperature
  • 2 1/2 c powedered sugar, sifted
  • 1 tsp vanilla bean paste (alt. use vanilla extract)
  • 1/2 tsp salt
  • 1/3-1/2 c crushed walnuts, lightly toasted

Instructions

brown butter pumpkin bars

  • To make the brown butter, melt butter in a clear heavy bottom pot. Once the butter starts to foam, whisk continuously until brown bits start to form. Remove from heat, pour into clean bowl, skim the foam from the top and cool to room temperature (30 minutes).
  • Line 9×13 baking pan with parchment paper and preheat oven to 350F. Whisk together flour, baking powder, baking soda, salt and pumpkin spice. Set aside.
  • In a stand mixer with paddle attachment, browned butter, and sugar until smooth and well combined. Add eggs, beating well after each one until well combined. Add pumpkin puree and vanilla bean paste, beating until well combined.
  • Add dry ingredients to the wet 1/2 batch at a time. Slowly beat each time until JUST combined. A few flour streaks is okay! Drop evenly sized scoops into the prepared pan. Evenly press batter/dough into the pan.
  • Bake at 350 for 35-45 minutes or until a toothpick inserted into the center comes out clean or with a few moist crumbs. Pull from the oven, and allow to cool min. 60 minutes. Pumpkin bars should be completely cool before frosting.

caramelized white chocolate mascarpone buttercream

  • Return caramelized white chocolate to liquid form by placing in a microwave safe bowl and heating in 20 second intervals (stirring after each) until melted. Cool to room temperature.
  • In a stand mixer, with paddle attachment, beat butter until light and fluffy, about 4-5 minutes. On the lowest speed, beat in the mascarpone cheese with butter until well combined. Go slowly or you risk the cheese breaking. Once combined, slowly beat in cool (but still liquid) caramelized white chocolate. Add powdered sugar, a generous tablespoon at a time, beating slowly to combine. After adding about half the powdered sugar, add in the salt and vanilla bean paste. Beat until well combined. Add the remaining half of the sugar, a generous tablespoon at a time, beating until well combined. Once all the sugar is added, beat frosting on med-high until smooth. Using a palette knife or spatula, spread frosting on top of cooled pumpkin bars.
  • To toast walnuts, line walnuts on a parchment lined baking sheet. Bake in oven at 350F for 8-10 minutes. Cool and roughly chop. Scatter on top of frosting.

Notes

pumpkin pie spice: Feel free to use a store bought version if you have one you like. If you’d like to make a homemade version, here is my preferred version: 
1/3 c ground cinnamon (32 g)
2 1/2 tbsp ground ginger (15 g)
2 tsp ground nutmeg (4g)
1 tsp ground allspice (4g)
1/2 tsp ground cardamon (1g)
Mix all ingredients together in a small mixing bowl. Store in an airtight container such as spice jar or small glass mason jar. 
browned butter: water evaporates from the butter while it is browning, accounting for the change in weight. If using melted butter, aim for 3/4 c or about 170g.
caramelized white chocolate: its preferred to use homemade for this, as you can adjust the level of caramelization to your tastes, however, it does require some advanced planning and about an hour of prep time. Worth it in my opinion. You can also use store bought, “golden” white chocolate which is basically the same thing. 

tips to make the perfect caramelized white chocolate

did you make this recipe?

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