Preheat your oven to 350°F (175°C) and prepare a baking sheet by lining it with parchment paper.
In a large mixing bowl, cream together the softened butter, brown sugar, and granulated sugar until light and fluffy.
Beat in the egg and vanilla extract until well combined.
In another bowl, whisk together the flour, baking soda, and salt. Gradually add the dry mixture to the wet ingredients, mixing until just combined.
Gently fold in the crushed pretzels, caramel candies, and milk chocolate chips until evenly distributed throughout the dough.
Use a cookie scoop or tablespoon to drop dough onto the prepared baking sheet, spacing them about 2 inches apart.
Sprinkle a few sea salt flakes on top of each cookie dough mound for an extra flavor burst.
Bake in the preheated oven for 10-12 minutes or until the edges are golden brown. The center might look slightly underbaked, which is perfect for a chewy texture.
Allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.