Sprinkle the yeast and 2 tablespoons of the sugar into the water or milk and stir to dissolve.
Place the flour on a work surface and make a well in the center. Add the yeast mixture, egg yolks, salt, cinnamon, and the remaining 2 tablespoons sugar. Knead well, about 5 minutes, working the butter or margarine into the dough and kneading until the dough is elastic. You can also use a food processor fitted with the steel blade to do this, processing about 2 minutes.
Put the dough on a greased bowl, cover with plastic, and let it rise overnight in the refrigerator.
Sprinkle flour of the work surface. Roll out the dough to an 1/8-inch thickness. using a 2-inch cookie cutter or floured drinking glass, cut out circles. Let the dough circles rise 15 minutes or more.
With your hands, gently form the dough circles into balls.
Pour 2-inches of oil into a heavy pot and heat until very hot, about 375 degrees.
Slip the doughnuts into the oil, 4 or 5 at a time, using a slotted spoon. Turn them when brown, after a few minutes, to crisp on the other side. Drain on paper towels.
Using a turkey baster, a pastry bag, or an injector, inject a teaspoon of jam into each doughnut. Then roll all of them in granulated sugar and serve immediately. You can make larger sufganiyot if you like.