In a large mixing bowl, stir together the masa, water, and salt. Cut in the butter or shortening using a pastry blender, food processor, or two knives, until the butter/shortening is the size of a pea.

Give the dough a small knead and form it into a disc. Turn the disc out onto a piece of plastic wrap. Wrap the dough and refrigerate for ten minutes.

Roll the dough out until about ¼ inch thick. Don’t worry about the shape. Cut the dough into 16, 3 ½ inch circles.

Sprinkle eight of the circles with a bit of queso fresco. Take the eight remaining circles of dough and cover the queso, slightly press down into the cheese, and pinch the edges together.

Heat a bit of butter on a griddle or in a large skillet over medium/high heat until it melts. Add each pupusa, one at a time, to the pan and cook for about three minutes each side until golden brown and a bit crispy.

Let cool on a paper towel until ready to serve.