# List of ingredients:
→ Cake Base
01 - 2 cups all-purpose flour
02 - 1 ½ teaspoons baking powder
03 - ½ teaspoon baking soda
04 - ½ teaspoon salt
05 - ½ cup unsalted butter, softened
06 - 1 cup granulated sugar
07 - 2 large eggs
08 - 1 teaspoon vanilla extract
09 - ¾ cup whole milk
10 - 2 medium apples, peeled, cored, diced
→ Cinnamon Swirl
11 - ⅓ cup brown sugar, packed
12 - 1 ½ teaspoons ground cinnamon
→ Crumble Topping
13 - ½ cup all-purpose flour
14 - ⅓ cup brown sugar, packed
15 - ½ teaspoon ground cinnamon
16 - ¼ cup unsalted butter, cold, diced
17 - ¼ cup chopped walnuts or pecans (optional)
# How to make it:
01 - Preheat oven to 350°F. Grease and line a 9-inch round springform or cake pan with parchment paper.
02 - In a bowl, whisk together all-purpose flour, baking powder, baking soda, and salt. Set aside.
03 - In a large bowl, cream softened unsalted butter and granulated sugar until light and fluffy using an electric mixer or whisk.
04 - Beat in eggs, one at a time, into the butter mixture and add vanilla extract.
05 - Gradually add dry ingredients to wet mixture, alternating with whole milk, starting and ending with flour. Mix until just combined.
06 - Fold diced apples into the batter using a rubber spatula.
07 - In a small bowl, mix brown sugar and ground cinnamon until well combined.
08 - Pour half the batter into the prepared pan. Sprinkle half of the cinnamon swirl mixture over the batter. Repeat layers with remaining batter and cinnamon swirl.
09 - Using a paring knife, gently swirl the cinnamon mixture through the batter for a marbled pattern.
10 - In another bowl, combine all-purpose flour, brown sugar, ground cinnamon, and cold diced butter. Rub together using fingers or fork until mixture resembles coarse crumbs. Stir in nuts if desired.
11 - Sprinkle crumble topping evenly over the cake. Bake for 45 to 55 minutes, or until a toothpick inserted in the center comes out clean.
12 - Allow cake to cool in the pan for 15 minutes. Transfer to a cooling rack before slicing.
