In a bowl, combine lukewarm milk and yeast. Let it activate for about 5-10 minutes, stirring gently.

In a large bowl, mix together the flour, sugar, salt, and softened butter. Then add the activated yeast mixture and eggs. Combine until a dough forms.

Knead the dough on a floured surface for about 10 minutes until it’s smooth and elastic.

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

Roll out the dough on a floured surface to about 1/2-inch thickness. Use a 3-inch round cutter to cut out circles. Place them on a baking sheet and let them rise for an additional 30 minutes.

Heat oil to 350°F (175°C) in a frying pan or deep fryer. Fry each doughnut for 2-3 minutes per side until they turn golden brown. Once cooked, drain them on paper towels to remove excess oil.

Using a pastry injector, carefully inject your choice of jam into each Berliner. Dust with powdered sugar before serving.