• Preheat an oven to 350 F. Grease and line two 9-inch round cake pans with parchment paper.
• Brown the butter. Add the butter to a small saucepan over medium-low heat. Let the butter melt and cook, swirling the pan every so often, until the butter is golden brown and smells nutty. Transfer to a heat-safe large glass mixing bowl and let it cool slightly.
• Mix the dry ingredients. In a separate mixing bowl, whisk together the flour, baking soda, kosher salt, milk powder, cinnamon, nutmeg, ground ginger, and cloves. Set aside.
• Mix the wet ingredients. Add the oil, brown sugar, molasses, and granulated sugar to the bowl with the slightly cooled brown butter. Whisk for 2 minutes, until the oil is well incorporated into the sugar. Whisk in the eggs, sour cream, and vanilla bean paste until very smooth. Switch to a rubber spatula and fold in the flour mixture, grated carrots, and walnuts until the batter has no streaks of flour.
• Bake the cakes. Evenly distribute the batter between the prepared cake pans. Bake for 30-35 minutes, until a toothpick inserted comes out clean. Let the cakes cool completely before removing them from the cake pans. If the cakes are domed, you can level off the tops with a serrated knife.
• Make the frosting. In a mixing bowl, combine the softened butter, vanilla, and cream cheese and use a hand mixer to beat them together for 2 minutes, until smooth. Gradually beat in the powdered sugar, adding cream as necessary when the mixture gets too thick. Whip the frosting until it’s smooth and spreadable.
• Frost the cake. Spread an even layer of frosting between the two cake layers. Then, apply a thin layer of frosting to the outside of the cake. Refrigerate for 20 minutes. Then, spread a thick and even layer of frosting around the rest of the cake. You can reserve some frosting to pipe decoratively around the cake. Let the cake chill for 1 hour before serving.

Storage Instructions

• To store: Leftover carrot cake can be stored, covered, overnight at room temperature or stored in a cake carrier in the fridge for 4-5 days.

  To freeze. Wrap individual cake slices in plastic wrap and then store in a freezer-safe ziplock bag to prevent freezer burn. Freeze for up to 3 months. Defrost slices overnight in the fridge.