I really don't have time to make 2 cakes. Did anyone ever collar a square cake pan? Do you recommend collaring cake pans in general? I just switched to 3" in my round pans to make bigger layers. Can I fill up the pan to the top when collaring?

Thank you in advance for your help!

Yes, you can collar a square pan, and fill it to the top as long as your collar is high enough for the amount of batter.I really liked the way my cakes turn out when collaring, I mean the side the are very nice and smooth, I have considered doing parchement around edges all the time.