For many years, I've assumed that I've been doing something wrong when I bake cookies. They always turn into these sad, flat cookie discs! Still yummy but not puffy, soft, and chewy on the outside like I like em.
I realized a few weeks ago that it had everything to do with the baking sheets I'd been using! I've been using some hand me down 10+ year old shiny metal sheets. I needed an extra pan so I used a new, nonstick cookie sheet and sure enough- a staggering difference. Same dough, same oven, only the sheet was different. These little chocolate chip peppermint bark cookies were world's better tasting too. Amazing.
So to anyone who's been plagued by sad, flat cookie discs... I recommend you invest in a new, nonstick cookie sheet.