Prep Pan & Water Bath: Preheat oven to 325°F (165°C). Grease a 9-inch springform pan and line the bottom with parchment. Wrap the exterior tightly with heavy-duty aluminum foil (or silicone pan guard) to prepare for a water bath.

Bake Spiced Oat Crust: Mix graham cracker crumbs, toasted oats, brown sugar, cinnamon, and melted butter until moistened. Press firmly into the bottom and 1 inch up the sides of the pan. Bake at 325°F for 10 minutes, then let cool.

Beat Cheesecake Batter: In a stand mixer fitted with paddle attachment, beat softened cream cheese and sugar on medium-low speed for 2 minutes until creamy and lump-free. Add sour cream and vanilla; mix until smooth. Beat in eggs one at a time on low speed, mixing just until incorporated (do NOT overbeat to avoid air bubbles).

Bake in Water Bath: Pour batter over cooled crust. Place springform pan in a large roasting pan and fill roasting pan with boiling water halfway up the sides. Bake at 325°F for 60 to 70 minutes until edges are set but center has a slight wobble.

Gradual Oven Cool & Chill: Turn oven off, crack door open 1 inch, and let cheesecake rest inside for 1 hour to prevent cracking. Remove, cool to room temp on wire rack, then chill in refrigerator for at least 6 hours or overnight.

Sauté Caramel Apple Topping: In a skillet over medium heat, melt 2 tbsp butter. Add apple slices, brown sugar, cinnamon, and nutmeg. Cook for 6-8 minutes until apples are tender and caramelized yet hold their shape. Cool completely.

Garnish & Serve: Spoon cooled spiced apples over chilled cheesecake, generously drizzle with warm salted caramel sauce, sprinkle with flaky sea salt, release springform ring, and slice!