POPE FRANCIS BLOWS IT ON HIS 81ST BIRTHDAY 13 foot Pizza Over Bday Cake?!?

Pope Francis might've committed a cardinal sin on his birthday -- blowing out a candle on a 13-foot pizza instead of a cake.

His Holiness turned 81 on Sunday and was treated to a 13-foot pizza with a single candle. Cool pic and all, but candles belong on pastries! A cupcake would've sufficed. That's a rule, right?

The kiddos seemed to be diggin' the bday bash -- even though someone at the Vatican couldn't even spring for pepperoni or sausage. Just cheese, Pontiff??!