Warm milk to lukewarm temperature.
Dissolve yeast in warm milk completely.
Mix flour, sugar, and salt together.
Add eggs to flour mixture gradually.
Pour yeast mixture into flour bowl.
Knead dough for 10 minutes until smooth.
Add softened butter while kneading continuously.
Place dough in greased bowl.
Cover with damp towel for rising.
Let rise for 2 hours until doubled.
Roll dough to 2cm thickness carefully.
Cut into 8cm circles using cutter.
Place on floured trays for second rise.
Cover and rise for 45 minutes.
Heat oil to 170°C for frying.
Fry bomboloni for 2-3 minutes each side.
Drain on paper towels immediately.
Make pastry cream while cooling completely.
Fill pastry bag with cooled cream.
Insert tip and fill each bomboloni.
Dust with powdered sugar before serving.