In a small bowl, dissolve yeast in warm milk and let it sit for 5–10 minutes until foamy.
In a large mixing bowl, combine flour, sugar, and salt.
Add egg yolks, melted butter, vanilla extract, and the yeast mixture to the dry ingredients.
Mix until a soft dough forms, then knead on a floured surface for 10 minutes until smooth and elastic.
Place dough in a greased bowl, cover, and let rise for 1.5–2 hours or until doubled in size.
Punch down dough, divide into equal portions, and shape each into a spiral or coil.
Place shaped rolls on a baking sheet lined with parchment paper, cover loosely, and let rise again for about 45 minutes.
Bake at 350°F (175°C) for 15–20 minutes, or until lightly golden.
Cool slightly and dust generously with powdered sugar before serving.