Step 1

Preheat the oven to 350ºF degrees. Line 2 baking sheets with parchment paper and set aside.

Step 2

Combine the flour, baking soda, cornstarch, and salt; stir with a whisk. Set aside.

Step 3

Combine melted butter and sugars in a large mixing bowl. Stir with a whisk until the mixture is smooth and free of clumps. Whisk in the egg, egg yolk, and vanilla.

Step 4

Add the flour mixture and stir just until well blended. Fold in the chocolate toffee pieces and butterscotch chips.

Step 5

Roll cookie dough into 1.5 tablespoons sized balls and place them 2 inches apart on the prepared baking sheets.

Step 6

Bake cookies for 12 minutes or until lightly brown and just underdone. Cool the cookies on the pan for 10 minutes. Remove from the pan and cool completely on a wire rack.