How to Make It
Heat oven to 375° F. Line 2 large baking sheets with parchment.
In a medium bowl, stir together the flour, oats, baking soda, and salt.
With an electric mixer, beat the butter and sugars on medium-high speed until creamy, 2 to 3 minutes. One at a time, beat in the eggs, then beat in the vanilla. Reduce the mixer speed to low and gradually add the flour mixture, mixing just until combined (do not overmix). Stir in the toffee pieces and chocolate chips.
Drop tablespoonfuls of the dough onto the prepared baking sheets, spacing them 2 inches apart. Bake until golden, about 8 minutes. Let cool slightly in the pans, then transfer to a wire rack to cool completely.
Storage suggestion: Keep the cookies at room temperature in an airtight container for up to 5 days.