Red Velvet Beet Bars with Brown Butter Sour Cream Frosting

 

The brown butter in the frosting and batter of these blondie-esque bars adds toffee-like richness to offset the earthy sweetness of the beets.

Ingredients

Cooking spray

1 1/2 cups unsalted butter (12 ounces)

1 large or 2 small red beets (about 12 ounces), peeled and chopped (1 1/3 to 1 1/2 cups)

2 teaspoons white vinegar

1 cup granulated sugar

1/2 cup packed light brown sugar

1 large egg, at room temperature

2 teaspoons vanilla extract, divided

1/2 teaspoon red gel food coloring (such as AmeriColor) (optional)

2 3/4 cups all-purpose flour (about 11 3/4 ounces)

1/4 cup unsweetened cocoa powder

1 teaspoon baking powder

1/2 teaspoon fine sea salt

1/4 cup sour cream

2 cups powdered sugar (about 8 ounces), divided

Directions

Preheat oven to 350°F. Coat a 9- x 13-inch baking pan with cooking spray; line bottom and sides of baking pan with parchment paper, leaving a 2-inch overhang on all sides. Coat parchment with cooking spray.

Melt butter in a medium saucepan over medium-low. Once butter is melted, increase heat to medium; cook, whisking constantly, until butter solids smell nutty and turn golden brown, 7 to 12 minutes. Transfer 1/2 cup brown butter to a small heatproof bowl. Refrigerate, uncovered, until solid, about 1 hour. Transfer remaining brown butter (about 3/4 cup plus 1 to 2 tablespoons) to a separate small heatproof bowl; let cool in refrigerator until butter is slightly warm to the touch, about 20 minutes.

Process beets and vinegar in a food processor until very finely chopped, about 2 minutes, stopping to scrape down sides of bowl as needed. Measure and reserve 3/4 cup processed beet mixture; discard any remaining beet mixture.

Process the slightly warm brown butter, reserved beet mixture, granulated sugar, and brown sugar in food processor until well combined, about 15 seconds. Add egg, 1 teaspoon vanilla, and food coloring, if using; pulse until smooth, about 5 pulses, stopping to scrape down sides of bowl as needed.

Whisk together flour, cocoa powder, baking powder, and salt in a medium bowl until combined. Add flour mixture to butter mixture in food processor; pulse just until combined, 10 to 12 pulses, stopping to scrape down sides of bowl as needed. (Mixture will be thick, like cookie dough.) Transfer dough to prepared baking pan, and pat into an even layer, using a sheet of plastic wrap to prevent dough from sticking to your hands.

Bake in preheated oven until top is set, edges are just starting to pull away from sides of baking pan, and a wooden pick inserted in center comes out mostly clean, 22 to 26 minutes. Remove from oven; let cool completely in baking pan on a wire rack, 45 minutes to 1 hour.

Meanwhile, beat reserved 1/2 cup chilled brown butter in a medium bowl with a hand mixer on medium-high speed until smooth and fluffy, 2 to 3 minutes, stopping to scrape down sides of bowl as needed. Add sour cream and remaining 1 teaspoon vanilla; beat on medium speed until well combined, about 15 seconds. Add 1/2 cup powdered sugar; beat on low speed until well incorporated, 30 seconds to 1 minute. Add remaining 1 1/2 cups powdered sugar, and beat on low speed until combined, about 45 seconds. Increase speed to high, and beat until fluffy, about 30 seconds. Spread frosting onto cooled red velvet bars. Using parchment paper overhang as handles, lift bars out of baking pan. Cut into 12 squares, and serve.