In a bowl, combine warm milk and sugar. Sprinkle the dry yeast on top, and let it sit for about 10 minutes until it becomes frothy.

In a large mixing bowl, whisk together the flour and salt.

Add melted butter and eggs to the yeast mixture, then mix well.

Gradually add the wet ingredients to the dry ingredients, mixing until a sticky dough forms. You may need to knead it a bit on a floured surface until smooth.

Place the dough in a greased bowl, cover it with a kitchen towel, and let it rise in a warm place for about 1 hour or until doubled in size.

After rising, punch down the dough and roll it out to about 1-inch thickness. Use a doughnut cutter or two round cutters to make doughnut shapes.

Let the shaped doughnuts rise again for about 30 minutes.

In a deep skillet, heat vegetable oil to 350°F (175°C).

Fry the doughnuts, turning them occasionally, for about 2-3 minutes until golden brown. Remove and drain on paper towels.

Using a piping bag, fill the doughnuts with custard, then dust with powdered sugar if desired. Enjoy warm!