A memory foam pillow with another insert inside the pillowcase with the cut-out seems to help me. I struggle to turn over, so once I'm wedged in, I'm usually there for the night.
I use a base pillow and tried a variety of different types of inserts/cut-outs to lay on top. I found a memory foam pillow worked the best, as my head kind of sinks in to it and it cradles my head enough to prevent me from sliding off or moving away from the cut-out. The piece of foam I used for the cut out is also memory foam, but a slightly firmer type- about 1 1/2" thick, cut to the same dimensions as my pillow and just tucked into the same pillowcase. Before that, I used that egg carton foam as a topper with no cut out and it worked pretty well too.