We always used to take these camping, and called them mini pie makers.
Our favorite recipes for making our own mini fruit pies, would either involve blueberries, or fresh apples cut up and mixed with brown sugar and cinnamon.
We would just buy the cheapest white bread to use for the crust, cutting off the edge of it once the clamshell was clamped tightly over the package of bread and fillings.
Back when we were not so conscientious about the food we ate, and didn’t have a good refrigerator system for camping, we often would make mini pies with bologna coupled with that fake American cheese slice stuff, or with chopped up hotdogs instead of bologna.
The nitrate laden bologna and hotdogs, and preservatives in the fake ‘cheese’ helped this gourmet repast stay somewhat edible longer in a ‘not quite up to safe temperature’ ice box with a quickly melting block of ice in it. 😁