Lay a few wontons out on a cutting board and place a wet paper towel over the remaining wonton wrappers to keep them from drying out.
Place a few marshmallows and chocolate chips into the center of each wonton wrapper.
Brush the edges of each wonton wrapper with a bit of water and then fold over into a triangle shape, pressing to seal and remove all air from the wonton.
Brush the two edges of the long side of the triangle with water and fold over each other, just above the center of the wonton, pressing the center of the wonton up to form a crease.
Repeat with all wonton wrappers.
Place the cooking oil in a heavy pan or dutch oven and heat to 300F.
Fry the wontons 3-4 at a time until lightly golden, flipping over halfway through cooking, about 3 minutes each batch.
Video
Notes
You can use an egg wash instead of water to seal the edges of a wonton wrapper. But, water also works just fine.
Make sure to squeeze the air out of your wontons before you seal them.
Be careful to not overheat the oil as that will cause the wontons to burn.
I lined a baking sheet with paper towels and allowed the excess oil to drain off the wontons onto the paper towels.