Preheat oven to 400°F.
Line a baking sheet with parchment paper.
Roll puff pastry into a 10-inch square or 10-inch round.
Place pastry on prepared baking sheet.
Score a 1/2-inch border around pastry without cutting all the way through.
Prick center of pastry lightly with a fork.
Combine apple slices, melted butter, sugar, lemon juice, vanilla extract, cinnamon and salt in a bowl.
Arrange apple slices neatly over center of pastry, staying inside scored border.
Bake until pastry is puffed and golden and apples are tender.
Warm apricot jam in a small saucepan or microwave.
Brush warm tart lightly with apricot jam.
Combine sugar and water in a small saucepan over medium heat.
Cook without stirring until sugar turns deep amber.
Remove pan from heat.
Whisk in butter carefully.
Slowly whisk in heavy cream.
Add vanilla extract and salt.
Return caramel sauce to low heat and stir until smooth.
Let tart cool until warm, not hot.
Slice tart into portions.
Drizzle each serving with caramel sauce.
Serve with vanilla ice cream.