Name: Caramel Apple Sheet Cake
Prep time: 45 min
Total time: 3 h 30 min
Yield: 12 serving(s)
Ingredients: Baking spray with flour, for the pan; 3 c. all-purpose flour; 1 tsp. baking powder; 1/2 tsp. baking soda; 1/2 tsp. ground cinnamon; 1/4 tsp. kosher salt; 1 c. vegetable oil; 1 c. packed dark brown sugar; 3/4 c. granulated sugar; 3 large eggs, at room temperature; 2 tsp. vanilla extract; 1/2 c. buttermilk, at room temperature; 2 medium Granny Smith apples, peeled and chopped; 2 tsp. flaky sea salt; 1/2 c. (1 stick) salted butter; 6 tbsp. buttermilk, plus more as needed; 2 1/2 c. powdered sugar; 1 tsp. vanilla extract

Step 1For the cake: Preheat the oven to 350°F. Spray a 13-by-9-inch baking pan with baking spray with flour.

Step 2In a medium bowl, whisk together the flour, baking powder, baking soda, cinnamon, and kosher salt.

Step 3In a large bowl, whisk together the oil, brown sugar, and granulated sugar until well combined. Whisk in the eggs, 1 at a time, until fully combined. Whisk in the vanilla. Gradually whisk in the flour mixture, alternating with the buttermilk, until no flour pockets remain and everything is just combined. Fold in the apples.

Step 4Pour the batter into the prepared pan. Use a rubber spatula to smooth the top. Bake until a toothpick inserted in the center comes out clean, 40 to 45 minutes.

Step 5Allow the cake to cool completely in the pan on a wire rack.

Step 6For the caramel frosting: In a medium saucepan, melt the butter over medium-low heat. Whisk in the brown sugar and cook, stirring constantly, until the sugar is mostly dissolved, 2 to 3 minutes. Increase the heat to medium and add ¼ cup of the buttermilk. Bring the mixture to a boil, stirring constantly, for 1 minute. Immediately pour the mixture into a medium heat-proof mixing bowl. Whisk in the powdered sugar, vanilla, and the remaining 2 tablespoons buttermilk until completely combined. If the mixture seems too stiff, add more buttermilk, 1 tablespoon at a time, until smooth and pourable.

Step 7Working quickly, pour the frosting over the cooled cake, spreading evenly. Allow the glaze to set for at least 1 hour and up to 1 day.

Step 8Before serving, sprinkle the cake with the flaky salt and slice it into 12 pieces.