In a mixing bowl with an electric mixer, combine the cake mix with the oats, oil, and eggs; beat on low speed just until moistened. Beat on high speed for a few seconds to blend thoroughly.
Fold in the toffee chips and chopped nuts.
Drop on the prepared baking sheet from a teaspoon or cookie scoop, leaving about 2 inches between cookies.
Bake for 10 to 12 minutes.
Let the cookies cool for 1 minute in the pan. With a spatula, carefully remove them to a rack to cool completely.