Ttump-en-tastically YUGE:
Copycat bakers have tried everything to get a cookie this thick, from loads of cornstarch in the dough to a grated hard-boiled egg. Most of these approaches overthink the problem of spread—which isn't a problem so much as a reflection of ingredient ratios.
Adding weird ingredients to reduce spread without adjusting the underlying formula is like trying to turn down the volume on a speaker by putting on earmuffs. It kinda works, but it's unnecessarily complicated compared with just...turning down the volume.
The easiest way to "turn down the volume" on spread in a cookie dough is to decrease the amount of sugar relative to the flour, as sugar is one of the primary factors governing spread in a cookie dough. With that change alone, most drop cookies will spread less as they bake, keeping the finished product nice and thick.