Pour the milk into a medium a saucepan , and bring to a simmer over medium heat. Do not boil the milk, once you notice small bubbles at the sides of the pan, remove it from heat.

While the milk is warming, in a medium bowl, mix the sugar and cornstarch, then mix in the egg yolks.

While constantly stirring, add one tablespoon at a time of the warm milk until you added all of it.

Pour the milk and egg yolk mixture back into the pan and cook over medium heat while constantly stirring until the cream has thickened.

Remove from the heat and keep stirring for additional one minutes then add the butter and vanilla extract and mix until smooth.

Pour the cream into an airtight container and refrigerate until use.

In a bowl of a standing mixer, place the flour, yeast, sugar, and salt, and use the paddle attachment to blend on low speed.

Add the eggs and water and mix until you have a shaggy mass, replace with the dough hook.

Knead the dough for additional 4-5 minutes, until the dough comes together into a ball and does not break.

With the mixer on medium speed, add the butter 1 tablespoon at a time, waiting for each piece to blend before adding the next.

Once you have added the last piece of the butter, increase speed to medium-high and knead until the bottom and sides of the bowl are clean and the dough is smooth.

Place the dough into a large oiled bowl, cover loosely with plastic wrap and refrigerate overnight.

Remove from the refrigerator and roll the dough into 1/2-1 inch thick.

Use 2-inch cookie cutter to cut the dough and place each piece over a 4x4-inch piece of parchment paper, then on a baking sheet.

Cover with pastic wrap and let rise for about 90 minutes, or until double in size.

Warm the oil in a large and deep pan until it reaches 350F (170C). Hold each donut by the parchment paper and gently place it in the hot oil, the parchment paper facing up.

Use kitchen toughs to remove the paper and fry each donut for 90 seconds on each side. Or until it reaches 180F (82C). Remove from the oil and place over paper towl. Allow the donuts to cool for about 15 minutes before filling.

Place the chocolate, and heavy cream in a medium heat proff bowl and warm in the microwave for about 30 seconds. Use a rubber spatula to mix until smooth, if needed warm it for additional 15 seconds. Mix in the corn syrup.

Fill a pastry bag with the cool pastry cream. Use a sharp knife, or a straw to make an insertion in each donuts then fill with the cream.

Hold each donut facing down, then dip it into the chocolate ganache.

Serve immediately.