Sufganiyot (Israeli Donuts)

Name: Sufganiyot (Israeli Donuts)
Prep time: 30 min
Cook time: 15 min
Total time: 45 min
Cuisine: Israeli
Ingredients: 1 cup warm water, (heated to about 110°F/43°C (see note)); 1 tablespoon instant/rapid-rise or active dry yeast ((note that this is more than 1 packet)); 3 cups all-purpose flour, (spooned into measuring cup and leveled-off); ¼ cup confectioners' sugar, (plus more for coating); ¾ teaspoon salt; ½ teaspoon ground nutmeg; 2 large egg yolks; 2 tablespoons vegetable oil, (plus about 2 qt (2L) more for frying); 1 teaspoon vanilla extract; About 1 cup jam or jelly ((or custard, Nutella, pudding, pumpkin butter, apple butter, dulce de leche, etc.), optional)