Salted Caramel Apple Pie Bars

Name: Salted Caramel Apple Pie Bars
Prep time: 25 min
Cook time: 45 min
Total time: 1 h 10 min
Cuisine: American
Ingredients: 1/2 cup (8 Tbsp; 113g) unsalted butter, melted; 1/4 cup (50g) granulated sugar; 1 teaspoon pure vanilla extract; 1/4 teaspoon salt; 1 cup (125g) all-purpose flour (spooned & leveled); 2 large apples, peeled and thinly sliced (1/4 inch thick)*; 2 Tablespoons (16g) all-purpose flour; 2 Tablespoons (25g) granulated sugar; 1 teaspoon ground cinnamon; 1/8 teaspoon ground nutmeg; 1/2 cup (43g) old-fashioned whole rolled oats; 1/3 cup (67g) packed light or dark brown sugar; 1/4 teaspoon ground cinnamon; 1/4 cup (31g) all-purpose flour (spooned & leveled); 1/4 cup (4 Tbsp; 56g) unsalted butter, cold and cubed; homemade salted caramel or store-bought caramel sauce; optional: flaky sea salt