All Grain Burns while mashing

[Keyser Soze]

I'm on my third batch of all grain bourbon mash and I have a problem with my mashing technique. I put cracked corn, wheat and rye ( 13 lbs, 2 lbs, 2lbs) in a BAYOU CLASSIC 15 gal stock pot full of 11 gals of boiling water. Before I get the chance to get the paddle in to stir it, it has stuck and started to burn on the bottom of the pot. The first time I caught it and stirred like a mad man for 2hours till it got soft and creamy, and then when the temp dropped to 165 F, added 3 lbs of malted 2 row and got great conversion. Ran it, saved it and was going to add to next run with the backset (25%). Then I burned the next mash, just a little, so I ran it, but without the saved distillate, ( I did use my backset though so it's gone) and as ecpected, it stunk like burned corn.. Saved the lot of it to act as antifreeze in my water tank for cooling my still. There's the story.

Any ideas on how to stop the burning on thebottom of the pot? I use a propane burner ala turkey fryer. Could I put a metal or aluminum plate under the pot. Pre malt, use less grain??? I'm running out of time for my stilly season.

Thanks, Eric