01 -
Line the bottom of a 9-inch springform pan with parchment. Spray the pan sides lightly. Heat the oven to 350°F, and adjust the rack slightly lower than the middle.
02 -
Combine the oats, melted butter, plain flour, both sugars, and cinnamon in a bowl. Use a fork to mix until tiny clumps form. Leave this on the side.
03 -
Stir the cinnamon and brown sugar together in a small dish. Set it nearby for later.
04 -
Dice the peeled apples into bite-sized chunks, roughly 1/3 to 1/2 inch wide. Throw them in a bowl with sugar and cinnamon, and mix well. Place aside.
05 -
Mix the flour, salt, and baking powder in a small bowl. In another bowl, beat butter, vanilla, and sugar until fluffy. Add eggs one at a time, mixing after each. Stir in sour cream, then gradually mix in the dry ingredients. Scrape the sides as needed.
06 -
Beat cream cheese until smooth with granulated sugar and vanilla added in. Mix in the single egg just until it's combined. Keep this on standby.
07 -
Spoon half the batter into the springform pan, spreading evenly. Add a layer of apple chunks and press them gently. Sprinkle with some cinnamon sugar. Pour the cream cheese mixture on top, avoiding the sides. Add another apple layer along with more cinnamon sugar. Finish by spreading the rest of the batter over, topping it with leftover apples, the crumble mixture, and more cinnamon sugar.
08 -
Bake for 70–90 minutes, checking after about 40–50 minutes. If it browns too fast, loosely cover with foil. Once a toothpick comes out clean, cool it for 20–30 minutes in the pan. Use a knife to separate the edges, then take off the pan's outer ring.
09 -
Stir together powdered sugar, milk (or cream), and vanilla until smooth. Drizzle it over the cooled cake. Store covered at room temp for one day, or refrigerate for up to a week.