Activate yeast: In a bowl add the yeast and warm water, stir it a bit and let it sit for 10 to 15 minutes to activate. You can also add 1 tbsp of sugar from the 1/2 cup of sugar needed for the dough, to help activate the yeast. The yeast should bubble up. If you don't see it bubble up, then the yeast is old. Do not proceed because your bread will not rise.
Combine wet ingredients: In a sauce pan add the milk, butter, lemon zest and sugar. Heat it over medium-low heat just until the butter melts and the sugar is dissolved. Do not boil it, it just needs to be warm to the touch. If it gets too hot it can kill the yeast. Remove from heat. Whisk in the eggs.
Make the dough: To the bowl of your mixer add the flour, the milk mixture, and the yeast mixture. Using the dough hook mix everything for about 5 minutes until everything is well blended together and the dough should come off the sides of the bowl. The dough will be a softer dough and somewhat sticky to your hands. The more you mix the dough the fluffier it will be.
Let the dough rise: Take a large bowl and oil it with about 1 tbsp of the vegetable oil. Place the dough in the bowl and use the other tbsp of vegetable oil to rub over the dough. Cover the bowl with plastic wrap and place in a warm, draft free environment. Let the dough rise until it doubles in size, could take 1 to 2 hours. Alternatively you could let the dough rise in the mixer bowl.
Prepare oven and baking sheet: Preheat the oven to 350 F degrees. Line a large baking sheet with parchment paper.
Divide dough: Divide the dough into 4 equal pieces. Take one piece and roll it into a 10 inch circle. Place it on the prepared baking sheet. Divide the other 3 pieces in half so that you end up with 6 pieces.
Braid the dough and let it rise: Roll each one into thin ropes about 3 feet long. Braid them and place them in the prepared pan in a circle around the edge of the 10 inch circle. Let this rise for a 2nd time until doubled in size.
Prepare the cheese filling: Make the cheese filling by mixing all the ingredients together. Pour this into the pasca (see pictures).
Bake: Brush the dough with egg wash and bake for about 40 to 45 minutes or until the crust is deep brown but not burnt.