Do I need additional time if I add a layer of frozen tots to the bottom as well as the top? Recipe calls for 50 mins @350 with just layer on top
I don't think you do. Tator tots usually don't take long to thaw. If anything, you could always take the temperature of the casserole dish (with meat thermometer) and add more time if needed. 165F is the safe temperature for cold foods that have to be reheated.