Heat oven to 375°F and lightly grease cookie sheet or line with parchment paper.
With a standard mixer with a paddle attachment, beat butter and brown sugar on high speed until well combined.
Add eggs and vanilla on medium speed and mix until just combined.
Add flour, baking soda, cinnamon and salt on slow speed and beat until just blended
Fold in oats and toffee bits with a large rubber spatula (so you do not over mix the dough with the mixer).
Drop 1 1/2 inch balls of dough on cookie sheet about 2 inches apart. These cookies will spread.
Bake 8 to 10 minutes or until edges are lightly browned.
Cool 1 minute; remove to wire rack.