Heat the oven to 400ºF and coat a 2-quart baking dish with cooking spray.
In a large bowl, toss the apple slices with the granulated sugar, lemon juice, and 2 tablespoons of flour. Spread the coated apples in the prepared baking dish.
In a food processor, combine the brown sugar, oats, cinnamon, butter, ⅓ cup of flour, and ¼ teaspoon of the salt. Pulse just until the mixture resembles coarse crumbs. Sprinkle the topping over the fruit in the dish and bake until golden brown and bubbly, 30 to 40 minutes. Remove the crisp from the oven and let it cool slightly.
Meanwhile, combine the caramel candies and milk in a 2-cup glass measure or bowl. Microwave the mixture on high just until it can be stirred smooth, 1 to 2 minutes, stopping every 30 seconds after the first minute of cooking. Cool the caramel sauce slightly; then drizzle it over each serving. Sprinkle each serving with some of the remaining ¼ teaspoon of salt.
Tip: To switch up the flavor here, replace the caramel sauce (caramel candies and milk) with ½ cup of prepared dulce de leche, warmed just until pourable.