First we'll begin by adding the yeast to the warm water in a small bowl. Let it sit until creamy, about 7-10 minutes.

In a large bowl, add the flour, salt and sugar. Make a well in the middle and add the wet ingredients: oil, yeast-water, milk and egg. The original recipe made double the amount, so here we only need half of the egg, so make sure not to add the entire egg in there.

Starting from the middle of the bowl, first mix the wet ingredients and gradually mix in the flour, continuing until all the flour is mixed and you have a nice dough. It shouldn't be too wet or too dry. After it is all incorporated, cover with cling film and let it rest until doubled in size, about 1.5 hours.

Halfway through the rise, turn on the oven to the highest temperature. The oven needs to be hot, hot, hot. You can use a pizza stone or turn a baking sheet upside down in the lower half of your oven (but not at the bottom).

When it has risen, separate the dough from the side of the bowl and add a handful of flour and knead the dough inside the bowl. It should be soft and pillowy. If the dough is too wet, continue adding flour.

Form into a ball, remove from the bowl and set aside to rest for 10 minutes.

While the dough is resting, combine the shredded mozzarella and crumbled feta. Remove 1/4 of the mixture and place it in a separate bowl and set aside. This will go on top of the bread.

In the larger bowl (with 3/4 of the cheese mixture), add one egg, 50 grams (1/4 cup) of butter, chopped spinach, and garlic and mix.

Putting it all together

Separate the remaining egg, saving only the egg yolk (you can use the egg white for meringues or a healthier omelette). Whisk it briefly in a small bowl and set it aside. It will be used to glaze the dough.

Place a large piece of baking paper on your counter and add some flour on top.

Now that the dough has rested, stretch the dough in a nice round shape and place it on top of the baking paper. Add the spinach and cheese filling in the center of the dough.

Fold up the edges around the filling and seal the dough. It should look like a ball. Now carefully flatten it by pushing down on the stuffed dough with your palms and finger tips. Make sure to create a lip or "ridge" around the edge of the dough, with a large "valley" in the middle where the cheese will sit.

Add the cheese in this "valley" and then glaze the "ridge" with the egg yolk. This will give the cheese stuffed bread a nice golden color.

The stuffed dough will be heavy. What I do is I slide the dough and baking paper on a sturdy cutting board, and then slide the baking paper and dough onto the pizza stone or upside-down baking sheet.

After about 5-7 minutes in the oven, the dough will puff up beautifully. Bake until the bread has a deep golden brown color and the cheese is brown and bubbling, about 15 minutes in total.

Remove carefully from oven by sliding the bread and baking paper on a cutting board. Take the remaining butter and slather it on the outside of the bread. You can slice immediately for the gooey cheese effect, or probably wait a few minutes so that you don't burn yourself.

Bon appetit!