Preheat oven to 350°F (175°C) and line a 12-cup mini muffin tin with liners.
Combine graham cracker crumbs and cinnamon, then mix in melted butter until crumbly. Press firmly into liners.
Beat cream cheese until smooth. Add sour cream and vanilla, then mix in sugars. Add egg and blend gently.
In a saucepan, cook apples with water, cinnamon, brown sugar, and salt for 5–7 minutes until tender-crisp.
Stir in cornstarch slurry and cook 1–2 minutes until thickened. Cool slightly.
Fill crusts with cheesecake batter, top with apple mixture, and bake 15–20 minutes until edges are set.
Cool, then refrigerate at least 2 hours before serving. This step ensures perfect Mini Apple Cheesecakes every time.