Preheat the oven to 400 degrees. Line a 9x13-inch pan with foil and lightly spray with cooking spray.
Prepare caramel (unless you're using jarred): Mix the caramel ingredients in a 2-quart saucepan. Heat over medium, stirring constantly, until it reaches the soft-ball stage (230 to 234 degrees). Remove from heat.
In a medium bowl, beat the brown sugar and the next 4 ingredients (through baking soda) until thoroughly combined. Mix in the flour, ground pecans and oats until crumbly. Scoop out 1 cup and set aside. Place the remaining crumbs into your prepared pan and press down firmly to coat the bottom.
Toss the apples in a large bowl with the salt and the cinnamon. Arrange them over the crust. Drizzle 1 cup of warm caramel over the top and then sprinkle with the remaining crumbs you set aside.
Bake 35 to 40 minutes until bubbly and the apples are just tender. Remove and let cool until they are just warm to the touch. Cut into squares. Try and let the bars rest until the caramel has set before serving. Drizzle individual servings with more caramel, if desired!
*The caramel recipe makes more than you will use for this recipe, so you can pour the rest into an 8x8-inch pan lined with foil and let cool. Cut into squares and you have your own homemade caramel squares!