Assume you mean for a single play ?
I got "QUIXOTIC" across the top left corner of the board, adding all but the 'O' when I was playing with my Mother many yers ago.
Let's see - Q=10 ; U=1 ; I=1; X=24 (treble letter score) ; O, T, I = 1 each and C=3; total 44 ; on TWO treble word scores = 396, plus 50 for all letters used.- 446.
Neither my Mother nor I could believe it ! - and I've never got anything like it before or since.
Couldn't believe it when I saw what I had (had been holding onto the Q from the start and only just got a U) and that Mum had placed an O just where I needed it on her last move !
648 tonight!!! the killer was making three variations of gunfighter across two triple word squares but i had a very strong game throughout!!! Im buzzin!!
Solitary play: 1220.