Spoon a tablespoon of filling in the center of each pancake. Fold both sides in towards the middle and roll up into a rectangular shape.
Melt enough butter in a skillet so blintzes float slightly over the butter. Fry the blintzes slowly on one side until golden brown, then turn and fry on the second side.
If the blintzes are frozen, don't thaw them. Fry them frozen, but keep the heat very low, cover the pan for the first 7 to 8 minutes, then turn them over and fry uncovered on the second side.
To bake, set them on a baking sheet and bake in a 425 degree oven until golden brown.