For the Crema Pastelera (Pastry cream):
In a large bowl, dissolve the yeast in the milk, then add the egg yolk, the 1 1/2 tbs sugar, the salt and the flour.
Once everything is well incorporated, add the butter and knead well forming a soft dough.
Cover and let it rest in a warm place for around 2 hours.
Roll out the dough in a floured surface until it's around 1 1/2 cm thick, cut circles around 10 cm diameter from it.
Moisten the edges of one of the circles (at this point if you like a jelly filling, place a teaspoonful on the first circle) and lay another one
on top of it. Press firmly to seal the edges.
Place the circles in lined baking trays and cover, let it raise for around 2 hours.
Fry in a deep fryer at 190 °C for 4 minutes on each side or until browned.
Drain on absorbent paper and sprinkle with sugar.
For the Crema Pastelera:
In a saucepan, bring the milk to a boil.
In the meanwhile, beat the egg with the sugar, add the flour (previously sifted with the cornstarch) and the add this mixture to the
saucepan with the milk.
Add little by little stirring constantly on low fire until the mixture becomes thick, remove from the fire add the vanilla and stir well.
Let it cool down, cover with plastic foil and refrigerate until cold before using.
Once the Sonhos are cold down, open a small hole in the middle and pipe the cream in the sonhos.