2 cups all-purpose flour
1 teaspoon baking powder
1 teaspoon baking soda
1 teaspoon ground cinnamon
1/2 teaspoon nutmeg
1/2 teaspoon ground cloves [I left this out because I don't like cloves]
1/2 teaspoon salt
3/4 cup unsalted butter, room temperature
1 1/2 cups sugar
3 large eggs, room temperature
1/2 cup buttermilk, room temperature
2 cups diced, peeled apples [I used Granny Smith]
1/2 cup walnuts, toasted and chopped
1 cup pure maple syrup
1/4 cup unsalted butter
1/2 heavy cream
1/2 teaspoon vanilla
2 cups powdered sugar
To make cake:
Sift together dry ingredients in a large bowl. In another large bowl, combine butter and sugar and beat on medium-high speed until light and fluffy, 3-5 minutes. Add eggs one at a time, beating well after each addition.
Using a rubber spatula, gently fold in 1/3 of flour mixture, until almost fully incorporated. Fold in 1/2 buttermilk, then fold in another 1/3 of flour mixture, followed by remaining buttermilk. Add remaining flour mixture, apples, walnuts, and using a light lifting motion and turning the bowl continuously, fold in until the batter is smooth and flour is thoroughly incorporated. Do not fold too vigorously or the cake will be tough.
Spread batter in a 9 x 13 buttered baking pan and bake at 350 degrees until top of cake is brown and toothpick inserted in center comes out clean - about 35-40 minutes. Transfer to wire rack to cool. Cool completely before frosting.
To make Maple Frosting:
In saucepan over medium-high heat, simmer maple syrup until it reduces by half, about 15 minutes. Stir in butter. Remove from heat and add vanilla and cream. Sift powdered sugar into a bowl, and pour maple mixture over sugar. Beat with whisk until smooth and creamy. Let cool completely before frosting cake.