LPT: DO NOT grease the pan when you're baking cookies (or any baked goods for that matter). That's what's burning your cookies.

I always ignored how the package on frozen cookies says "ungreased baking sheet", because I thought that it prevented them from sticking to the pan. But I forgot to spray the sheet with butter one day, and I realized that the cookies weren't burned/crispy at the bottom. Turns out the butter on the pan was the culprit for having cookies that were dark at the bottom.