Preheat your oven to 325°F (165°C).
In a large bowl, cream together the unsalted butter and granulated sugar until light and fluffy.
Mix in the vanilla extract until well combined.
In a separate bowl, whisk together the flour, cornstarch, and salt.
Gradually add the dry ingredients to the butter mixture, mixing until just combined.
Fold in the chocolate chips and toffee bits until evenly distributed.
Scoop tablespoon-sized portions of dough onto a parchment-lined baking sheet, spacing them about 2 inches apart.
Gently flatten each cookie with the back of a fork, pressing slightly to create a decorative pattern.
Bake for 15–18 minutes, or until the edges are lightly golden.
Remove from the oven and allow the cookies to cool on the baking sheet for 10 minutes before transferring them to a wire rack.
