Preheat oven to 375 degrees F. Line a rimmed baking pan with parchment paper.

Core and thinly slice apple; coarsely chop slices. You should have about 2 cups. In a large bowl, toss apples with sugar, flour, lemon juice, cinnamon, and nutmeg. Dust work surface with flour.

Soften 1 pie crust as label directs; unroll crust. Cut into 9 circles using a 3-inch round cutter or glass. Gather dough scraps; with a rolling pin, roll out scraps and cut 3 more circles.

Place about 2 tablespoons apple filling and 2 pieces caramel in the center of 6 circles; top each with remaining 6 circles. Seal edges of pies with fork; transfer pies to the prepared pan. Repeat process with remaining pie crust to make 6 more pies.

In a small bowl, whisk egg; evenly brush tops of pies with egg and sprinkle with salt. With a paring knife, cut 2 vents in the top of each pie. Bake pies 30 to 35 minutes or until golden brown.