Dissolve the yeast in warm water with 1 tsp sugar; let sit 5–10 minutes until foamy.
In a large bowl, combine the flour, remaining sugar, and salt. Add yeast mixture, warm milk, eggs, and butter. Mix to form a soft dough. Knead 5–7 minutes until smooth. Cover and let rise 1–2 hours, until doubled. Roll dough to 1/2 inch thick; cut into 2-inch rounds. Let rest for 15 minutes.

Heat oil to 350°F. Fry doughnuts 1–2 minutes per side until golden. Drain on paper towels. Using a small piping tip or spoon, fill each doughnut with jam. Dust with powdered sugar and serve warm. Enjoy!