My 2c.....Just so happens, one of my FAVORITE local pies here in the Mpls/St Paul area is a sturdy Chicago thin crust style pie. And I used to buy a LOT of half baked from him, wrapped in plastic and ordered 10 or more at a time, for 1/2 the menu price! As CDNpielover will attest to, Red's Savoy Pizza is one of the top 5 pizzas in the Twin Cities. Since my own pizza making hobby and skills have improved over the years I don't stock up on the frozen ones much anymore but I would not hesitate getting them for an event to thaw and heat and eat anytime. Sooooo, that brings me to how I handle theirs or any pre-frozen pie including store bought.
If you have a stone, use it. Pre-heat oven to 450-550° depending on how you know that particular pre-froze pie will bake up
Leave pie wrapped in the plastic and thaw to room temp. Leaving to thaw IN THE PLASTIC keeps the pie and especially the crust from getting wet from the condensation of thawing. This applies to par-baked or from a raw froze one as say a Papa Murphy's. Mind you I haven't tried freezing Papa Murphy's, just comes to mind as I type. I prefer them to a Domino's or Pizza Hut for quality bang for buck.
Unwrap, slide onto a floured peel and into the oven til done. In the case of a Papa Murphy type, leave on their bake proof card board thingy and onto a stone
I find just a little extra fresh cheese just before baking preferable as the ones that are frozen the longest will suffer from the cheese getting a little dried out.
Another way is frozen pie into a cold oven on a regular pizza pan of choice and the turn oven at the hottest it will go and pull when done. I prefer the thawed method, both work well. I used to go through a LOT of these in the old days 30+ years ago, still one of my FAVORITE pizza joints to eat at. 60's decor, dive type of joint, needs the local drunks smoking at the bar (they still drink there) and the place is packed with people standing in line for a table every nite!!! Savoy's par-baked and frozen pies, re-heated at home, are better than 90% of what most people can make on their own. REALLY great pizza!!!
Now for re-heating leftover slices of ANY pie, pre-heated cast iron skillet on low-med heat with a heat diffuser underneath pan, heat till bottom is unbearably crispy and toppings are melted, cover as needed while heating. BEST way for the patient eater to reheat pizza, crust will shatter!!!!