Zucchini Layer Cake with Tangy Buttercream Frosting

Ingredients

• 1.5 teaspoons double-acting baking powder 
• 1 teaspoon baking soda 
• 3 cups cake flour such as softasilk, plus more as needed
• 1 cup t brown sugar dark packed
• 4 large eggs at room temperature
• 1 cup granulated sugar 
• 1.5 teaspoons ground cinnamon 
• 0.5 teaspoon nutmeg freshly ground
• 8 ounces pecans toasted finely chopped
• 1.8 cups powdered sugar 
• 0.3 teaspoon salt fine
• 1 cup nonfat greek yogurt plain at room temperature
• 10 servings butter unsalted for coating the pans
• 1 tablespoon vanilla extract 
• 1 cup vegetable oil 
• 3 cups zucchini grated ends trimmed ( 3 to 4 medium zucchini)

Equipment

• bowl
• baking sheet
• baking paper
• oven
• knife
• whisk
• plastic wrap
• toothpicks
• cake form
• stand mixer
• spatula
• offset spatula

Directions

1. Heat the oven to 350°F and arrange a rack in the middle.
2. Cut out 2 (8-inch) rounds of parchment paper; set aside. Coat 2 (8-inch) cake pans with butter, place the rounds in the pans, and coat the parchment with more butter. Coat the pans and parchment with flour and tap out any excess; set aside.
3. Place the measured flour, baking powder, cinnamon, baking soda, nutmeg, and salt in a large bowl and whisk to aerate and break up any lumps; set aside.
4. Combine the eggs, sugars, oil, and vanilla in a second large bowl and whisk until the eggs are broken up and the mixture is thoroughly combined. Using a rubber spatula, fold in the flour mixture until just combined. Fold in the zucchini until evenly mixed.Divide the batter evenly between the prepared pans.
5. Bake side by side on the middle rack, rotating from one side to the other halfway through the cooking time, until a cake tester or toothpick inserted in the center comes out clean, about 40 to 45 minutes.
6. Place the butter and sugar in the bowl of a stand mixer fitted with a paddle attachment and beat on low speed until the sugar is incorporated, about 30 seconds.Increase the speed to medium high and beat until the mixture is light in color, about 3 minutes. Stop the mixer and scrape down the sides of the bowl and the paddle.Return the mixer to medium-high speed and add the vanilla and salt.
7. Add the yogurt 1/3 cup at a time until all of it has been added, then continue mixing until the frosting is evenly combined and light in texture, about 3 minutes. (It’s very important that the yogurt is at room temperature, or the frosting will seize and form clumps.)For the filling, transfer 1 1/4 cups of the frosting to a medium bowl and mix in 2/3 cup of the pecans; set aside.To frost the cake, place a layer on an upside-down cake pan. Evenly spread all of the nut filling over the top of the layer, then place the second cake layer on top, cut-side down. (This way you have a really smooth, even surface to frost.) Using an offset spatula or long, thin knife, spread the remaining frosting evenly over the top and sides of the cake. Using your hands, gently press the remaining 1 1/3 cups pecans into the frosting around the sides of the cake. (It’s helpful to do this over a baking sheet to catch any falling pecans.) Carefully slide 2 long, flat spatulas under the cake from opposite directions, lift the cake off the cake pan, and transfer it to a serving plate. If you don’t plan to eat the cake within 4 hours, tent it with plastic wrap and refrigerate it for up to 3 days. To serve, let the cake sit at room temperature for about 45 minutes to take the chill off before slicing.