1. Preheat oven: Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper or a silicone baking mat.

2. Cream the butter and sugar: In a large mixing bowl, beat the softened butter and sugar together until light and fluffy, about 2-3 minutes.

3. Add egg and vanilla: Add the egg and vanilla extract, and beat until combined.

4. Mix dry ingredients: In a separate bowl, whisk together the flour, baking soda, cinnamon, and salt. Gradually add the dry ingredients to the butter mixture, mixing just until combined.

5. Fold in apples and oats: Gently fold in the diced apples and oats (if using). The dough will be soft and slightly sticky.

6. Shape and bake: Scoop about 2 tablespoons of dough for each cookie and roll them into balls. Place them on the prepared baking sheet about 2 inches apart. Slightly flatten the dough balls with your fingers or a spoon.

7. Bake the cookies: Bake for 10-12 minutes, or until the edges are golden brown and the centers are set. Allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.

Make the Caramel Drizzle:

8. Heat the caramel drizzle: In a small saucepan, heat the heavy cream over medium heat until it just begins to simmer. Remove from heat and stir in the caramel sauce until smooth and combined.

9. Drizzle on the cookies: Once the cookies are fully cooled, drizzle the caramel sauce over the top of each cookie using a spoon or small piping bag.