Caramel Apple Strata

Name: Caramel Apple Strata
Ingredients: FOR THE VANILLA SAUCE:; 2 cups milk; 1 vanilla bean, halved lengthwise, seeds scraped and reserved; 6 egg yolks; ¼ cup sugar; 6 tbsp. unsalted butter; 5 medium baking apples, such as Golden Delicious, peeled, cored, and quartered; ¾ cup packed light brown sugar; 1 ½ tsp. ground cinnamon; ¼ tsp. freshly grated nutmeg; Juice of ½ a lemon; ¾ cup sugar; ¼ tsp. kosher salt; 3 eggs; 1 ½ cups heavy cream; 2 tsp. vanilla extract; 1 Italian or French bread loaf or baguette (about 15 oz.) cut crosswise into ½ slices