Preheat the oven to 350 degrees.
Melt the butter and place it in an electric mixer. Scrape the sides of the bowl you used to melt the butter so you have all you need.
Add in the egg and bag of cookie mix.
Turn the mixer off and add in the Brewer's Yeast and Flaxseed. Mix again for about a minute. The consistency should be thicker than normal cookie mix, but not too hard to scoop.
Scoop the cookies out onto a greased baking sheet and bake for 8 to 12 minutes, depending on your oven. I love having a cookie scoop to make the shape rounded.