Irish Apple Cake

Step 1
Combine 1/2 cup flour, 1/2 cup sugar, oats, 1/4 teaspoon salt, and 1/4 teaspoon cinnamon in a bowl for the streusel. Using a fork or pastry cutter, cut butter into the mixture until it is fully incorporated and has the texture of coarse bread crumbs, about 2 minutes. Chill in the refrigerator until ready to use.

Step 2
Preheat the oven to 350 degrees F (175 degrees C). Grease a 9-inch round cake pan with cooking spray.

Step 3
Combine 1/2 cup butter, 1/4 cup granulated sugar, and brown sugar in a medium bowl for the cake batter. Beat at medium speed, until lightened in color and fluffy, 3 to 4 minutes. Beat in eggs, 1 at a time, on low speed, just until blended. Beat in vanilla extract.

Step 4
Combine 1 1/4 cups flour, baking powder, 1 teaspoon cinnamon, and 1/4 teaspoon salt in a small bowl. Add dry ingredients to the mixing bowl and mix on low speed until fully incorporated, 1 to 2 minutes. Add 3 tablespoons milk and beat on low speed until combined, about 45 seconds.

Step 5

Step 6
Arrange apple slices evenly on top of batter, overlapping as needed.

Step 7
Sprinkle apples with streusel.

Step 8
Bake in the preheated oven until a toothpick inserted into the center comes out clean and streusel is golden brown and crisp, 40 to 50 minutes. Let cake cool in pan on a wire rack 10 minutes. Remove from pan to wire rack and let cool completely, 30 to 45 minutes.

Step 9
Whisk together powdered sugar, 1 teaspoon cinnamon, and 2 teaspoons milk in a small bowl until smooth.

Step 10
Drizzle glaze over cake before serving.