Preheat your oven to 375°F (190°C) and grease a large baking pan.
In a food processor, pulse flour, baking powder, sugar, salt, and cold butter until crumbly.
Add eggs and ice water to the processor, pulsing until the dough just comes together.
Press two-thirds of the dough into the bottom of the prepared pan and bake for 10 minutes.
While the base bakes, melt 2 tbsp butter in a skillet over medium heat.
Add diced apples, brown sugar, vanilla, and cinnamon to the skillet and cook until slightly tender.
Spread the cooked apples over the partially baked base.
Crumble the remaining dough over the apple layer and bake for 25-30 minutes until golden.
For the caramel, heat 1 1/2 cups sugar in a pan until melted and amber, then carefully stir in 1/2 cup butter and heavy cream until smooth.
Remove caramel from heat, stir in sea salt flakes, and drizzle over the cooled bars before serving.