Preheat oven to 350 degrees Fahrenheit. Grease a 9-inch springform pan with cooking spray. Set aside.

Make Streusel: Place the flour, sugar, oats, and cold butter in a large bowl. Rub butter into dry ingredients with your fingers or cut the butter with a pastry blender or fork until a coarse, crumbly texture is achieved. Set prepared streusel in the fridge until ready to assemble the cake.

Prepare Apples: Peel, core, and thinly slice apples. Cover sliced apples with a towel or toss with 1 tsp of lemon juice to prevent browning. Set aside.

Make Cake Batter: Sift the flour, baking powder, cinnamon, and salt with a fine mesh sieve. Set aside.

Cream the butter and sugar together with an electric mixer.

Add the eggs one at a time, mixing until incorporated after each addition.

Add half of the dry ingredients. Mix until almost incorporated (about 5 seconds). Add all of the milk. Mix until just incorporated (approximately 5-10 seconds). Stir in the remaining dry ingredients until just incorporated. Do not over-mix.

Assemble the cake: Spread the cake batter evenly into the prepared pan. Layer the apples evenly over the cake batter. (No need for a pretty presentation, just make sure it’s even.) Sprinkle the streusel over the top of the apples.

Bake the Irish apple cake at 350˚F for 45-55 minutes until the top/edges are lightly browned. You can test the cake with a toothpick, but it’s hard to tell if the batter is done through the layer of apples. I like to do the finger test. Press the middle of the cake down with one finger, if it springs back it is done. The streusel will be hot, so be careful.

Allow cake to cool slightly in the pan before removing it. Dust with powdered sugar before serving.