In the bowl of a stand mixer fitted with the paddle attachment, beat the butter, brown sugar, and granulated sugar together until creamy, about 1 minute.

Add the egg, egg yolk, and vanilla extract, mixing until well combined.

Add the cornstarch, baking soda, salt, and flour; mix until a soft dough forms.

Stir in the crushed pretzels, white chocolate chips, and caramel bits until evenly distributed throughout the dough.

Cover the dough and refrigerate for at least 1 hour to firm up.

Preheat the oven to 350 °F (175 °C). Line baking sheets with parchment paper or silicone liners.

Drop rounded heaping tablespoons of dough onto the prepared sheets about 2 inches apart.

Bake for approximately 8–10 minutes, rotating the pans halfway through to ensure even baking.

Allow cookies to cool on the sheet for about 10 minutes, then transfer to a wire rack to cool completely.