Nonstick vegetable oil spray
1 cup sugar
1/4 cup (1/2 stick) unsalted butter, cut into small cubes
Crystal flake sea salt (recommended: Maldon)
7 to 8 medium Golden Delicious apples
1 lemon, juiced
1/2 (17.3-ounce) package or 1 sheet frozen puff pastry, thawed
Flour, for dusting
Vanilla ice cream, for serving, optional