Preheat your oven to 350°F (175°C). Line baking sheets with parchment paper or a silicone mat (Silpat).

In a large bowl, beat the room-temperature butter and shortening with an electric mixer until fluffy, about 2–3 minutes. Add the brown sugar and beat until well combined.

Beat in the eggs and vanilla. Stop to scrape the bowl, then continue mixing on medium-high for about 1 minute more, until the mixture is lighter in color.

In a separate bowl, whisk together the oats, flour (remember scoop and sweep), baking soda, baking powder, cinnamon, and salt.

Add the dry ingredients to the wet in three additions, mixing just until incorporated after each addition. Avoid overmixing.

Gently fold in the toffee bits. Cover the bowl and refrigerate the dough for 30 minutes to reduce spread and deepen flavor.

Use a 1 tablespoon cookie scoop to portion dough onto prepared sheets, about 3 inches apart.

Bake for 13–15 minutes until the edges are golden; the centers will look pale and slightly underbaked.

Let cookies cool on the baking sheet for about 5 minutes, then transfer to a cooling rack to finish cooling.