In a small container, mix the yeast, sugar, flour, and warm milk.
Mix until smooth and set aside.
Note: Do not use HOT milk. Warm milk only.
In a large mixer, add the flour, sugar, salt.
Mix together to combine.
If you are using a KitchenAid, use the hook attachment.
Add the eggs, egg yolks, and orange zest.
Start mixing slowly.
Gradually add the butter.
Once the butter is fully combined, add the yeast mixture.
Mix for a few minutes.
On a clean surface, dust with flour.
Add the dough.
The dough will be very sticky.
Start working the dough by hand.
It will take roughly 20 minutes to get the dough to come together.
It will look sticky. Have faith. The dough will come together.
When your hand no longer sticks to the dough, it is ready.
Butter a bowl.
Add the dough to the bowl.
Cover with plastic wrap or a kitchen towel.
Proof for 1 ½ hour.
Note: if you live in colder climates, you might need to proof longer.
Dust a clean surface with more flour.
Roll out the dough as far as it can go.
It will look like a long baguette.
You can use a rolling pin.
Make a hole on one end of the dough.
Connect one end of the dough to the end with the hole.
Shape the dough into an oval.
Eyeball the size of the oval dough in comparison to your cookie sheet.
If it's too big, cut the dough and make two Rosca de Reyes
Carefully place the dough onto a buttered cookie sheet.
Shape again into an oval form.
Cover and set aside.
Make the sugar topping by combining the powdered sugar, butter, 1 cup flour, cinnamon, and vanilla.
Mix until a small ball forms.
Dust a clean surface again with flour.
Roll out the sugar topping.
With a knife, cut into small equal-sized rectangles.
Make the egg wash by mixing an egg with water.
Brush the dough with the egg wash.
Be sure to brush the sides of the dough.
Add the sugar toppings and desired decorations.
Cover while heating the oven.
Heat an oven for 350 degrees F.
Uncover the dough and bake for 30 minutes.
Let cool before serving.