Brown Butter Carrot Sheet Cake with Brown Butter-Cream Cheese Frosting

1 . Stage

Place butter in a light-colored saucepan over medium heat. Cook, swirling the pan constantly, until butter is bubbling, smells nutty, and browned bits begin to form on the bottom of the pan, 5 to 10 minutes. Immediately remove from heat and pour butter into a heat-safe bowl. Allow brown butter to cool to room temperature, about 15 minutes.

2 . Stage

Preheat the oven to 325 degrees F (165 degrees C). Grease a 12x16-inch pan and line with parchment paper.

3 . Stage

Whisk together flour, baking soda, baking powder, cinnamon, allspice, nutmeg, and salt in a bowl.

4 . Stage

Beat cooled brown butter and brown sugar in a large bowl with an electric mixer on medium speed until well combined. Beat in eggs, one at a time, mixing well after each addition, until mixture is light and fluffy. Mix in vanilla. Pour in 1/2 of the flour mixture and mix until just combined. Add in remaining flour mixture and mix until just combined.

5 . Stage

Fold in shredded carrots, walnuts, and raisins. Pour batter into the prepared pan and smooth out the top with a spatula.

6 . Stage

Bake in the preheated oven until cake is golden and a toothpick inserted into the center of it comes out clean, 23 to 27 minutes. Transfer onto a wire rack and cool completely, about 30 minutes.

7 . Stage

While cake is cooling, repeat step 1 to brown butter for the frosting. Let cool to room temperature, about 15 minutes.

8 . Stage

Beat cream cheese in a large bowl with an electric mixer on medium-high speed until completely smooth. Add in cooled brown butter and mix until thoroughly combined. Mix in powdered sugar, 1 cup at a time, beating well after each addition. Mix in vanilla and salt. Beat frosting at medium-high speed until completely smooth, 1 to 2 minutes.

9 . Stage

Spread frosting over the cooled cake. Chill cake until ready to serve.