Prepare the Yeast Mixture:
In a bowl, mix warm water, active dry yeast, and granulated sugar. Let it sit for about 10 minutes until it becomes bubbly and frothy.

Make the Donut Dough:
In a mixing bowl or stand mixer, combine all-purpose flour and granulated sugar. Add the egg yolks, soft butter, and milk. Once the yeast mixture is ready, add it to the bowl with the other ingredients.

Knead the Dough:
Knead the dough with a stand mixer using the dough hook for 15-20 minutes on medium speed, until smooth and elastic.

Proof the Dough:
Place the dough in a greased bowl and proof for 1½ hours in a warm environment (around 84°F or 29°C). The dough should double in size.

Shape the Donuts:
Once the dough has risen, roll it out to about 0.25 cm (0.1 inches) thick. Use a 6 cm (2.36 inches) cookie cutter to cut the dough into donut shapes. Let the donuts proof again in a warm place for 30 minutes, until they become puffy and about 0.5 cm (0.2 inches) thick.

Fry the Donuts:
Heat the oil to 180°C (356°F) for frying. Keep the oil temperature at 175°C (347°F) as you fry the donuts. Fry the donuts for about 2 minutes on one side, flip them, and cook for another 2 minutes. Flip again to cook until golden brown and crispy.

Drain the Oil:
Remove the donuts from the oil and place them on a plate lined with paper towels to drain excess oil.

Prepare the Cheesecake Filling:
In a bowl, mix together cream cheese, powdered sugar, and strawberry jam until smooth and combined.

Assemble the Donuts:
Once the donuts have cooled slightly, pipe or spoon the cheesecake filling into the center of each donut.

Decorate:
Garnish the donuts with fresh strawberries and a light dusting of powdered sugar.