Step 1: Prep Apples
Peel, core, and halve apples. Arrange halves in bowl cut-side-up.

Step 2: Make Caramel
In a 10-inch oven-safe skillet, melt sugar over medium heat, swirling pan to create even amber caramel (~8–10 min). Add butter cubes and stir until smooth. Remove from heat, stir in cinnamon or vanilla.

Step 3: Arrange Apples
Place apple halves rounded-side-down, packed tightly. Smooth top flat; drizzle any residual sugar-butter over.

Step 4: Add Pastry Layer
Lay pastry over skillet, tucking edges around apples. Trim excess, seal gently.

Step 5: Bake
Preheat oven to 375°F. Bake 35–45 min until pastry is puffed and golden, juices bubbling.

Step 6: Prepare Nutmeg Cream
While baking, whisk yolks and sugar. Scald cream with nutmeg; slowly combine with yolks, then back to stove. Cook, constantly stirring, until thick enough to coat spoon. Cool slightly.

Step 7: Invert Tarte
Rest skillet 5 min. Place plate over skillet, invert quickly but carefully. Let rest another minute, then lift skillet.

Step 8: Serve
Slice tart and serve warm with generous spoonfuls of nutmeg cream. Spruce up with optional garnishes.