Prep the pan and oven: Heat oven to 325°F (165°C). Line the bottom of a 9-inch springform pan with parchment, and lightly grease the sides.
Wrap the outside with foil if your pan leaks.
Make the crust: In a bowl, mix 1 cup rolled oats, 3/4 cup almond flour, 2 tablespoons brown sugar, 1 teaspoon cinnamon, and a pinch of salt. Stir in 4 tablespoons melted butter and 1 teaspoon vanilla. Press the mixture firmly into the pan bottom.
Bake 8–10 minutes until lightly set. Cool slightly.
Cook the apples: Peel and thinly slice 2 apples. Toss with 1 teaspoon lemon juice, 1 teaspoon cinnamon, a pinch of nutmeg, and 1–2 tablespoons maple syrup.
Sauté over medium heat 5–7 minutes until tender but not mushy. If there’s excess liquid, stir in 1/2 teaspoon cornstarch and cook 30–60 seconds to thicken. Cool to lukewarm.
Blend the filling: In a large bowl, beat 16 ounces softened reduced-fat cream cheese until smooth, about 1 minute.
Add 1 cup Greek yogurt, 1/2–2/3 cup granulated sweetener, 1 scoop (25–30 g) vanilla or unflavored protein powder, 1 teaspoon vanilla, 1 teaspoon cinnamon, and a pinch of salt. Mix on low until combined. Beat in 2 large eggs, one at a time, on low speed just until incorporated.
Do not overmix.
Layer it up: Spread half the cheesecake batter over the crust. Arrange half the apples evenly over batter. Add remaining batter, then top with the rest of the apples.
Gently press apples in so they’re slightly submerged.
Bake: Tap the pan gently on the counter to release bubbles. Bake at 325°F for 40–50 minutes, until the edges are set and the center has a slight wobble. The top should look matte, not wet.
Cool slowly: Turn off the oven, crack the door, and let the cheesecake sit for 30 minutes.
Move to a rack and cool to room temperature. This helps prevent cracks.
Chill: Cover and refrigerate at least 6 hours, preferably overnight. It will firm up and slice cleanly.
Serve: Run a knife around the edge, release the springform, and slice with a warm, clean knife.
Add extra sautéed apples or a light caramel drizzle if you like.