You can omit the corn syrup. It will change the texture slightly!

You can do all butter, but it will change the texture slightly (no buttery crisp edge).

Yes, you can do all butter instead! It will change the texture of the cookie slightly, but will still be delicious!

I recommend always baking a test cookie to make sure they are turning out how you want them to! If your cookies aren’t spreading, a quick fix is to flatten the dough balls slightly before baking or whack the pan against the counter after baking.

I use room temperature, softened butter.

Absolutely! You can use any substitute you’d like. I recommend starting with vegetable oil, but applesauce should work too (although I haven’t tested it in this specific recipe).