2. Add the butter, egg and water until a clumpy dough forms.
3. Form a ball and chill in the refrigerator for about 30 minutes.
4. Roll out the dough into a thin sheet and cut out round disc shapes for empanadas (use round molds or a small plate).
5. Use immediately or store in the refrigerator or freezer to use later.
6.Sautee the bacon or pancetta until it is crispy and golden, drain to remove any excess grease but reserve a couple tablespoons of the grease to cook the leeks.
7. Fry the leeks in the grease reserved from the bacon or pancetta and let them cook until they are tender, about 10 minutes on medium heat, stirring occasionally.
8. Once the pancetta and leeks have cooled down combine them in a bowl with the grated cheese, raisins, nutmeg, salt if needed, and pepper.
9. To assemble the empanadas spoon the leek mixture on to the center of the each empanada disc.
10. Brush the edges of the empanada discs with the egg whites, you can also use water but the egg white is a good natural “glue” that helps seal the empanada.
11. Fold the empanada disc and seal the edges gently with your fingers, twist and fold the edges of the empanadas with your fingers, as a final step use a fork to press down and finish sealing the empanadas.
12. Lightly brush the top of the empanadas with the egg yolk; this will give them a nice golden glow when they bake.
13. Let the empanadas rest in the refrigerator for at least 30 minutes or until ready to bake, this will help them seal better and prevent leaks.
14. Pre-heat the oven to 400 F and bake for 20-25 minutes or until golden, exact time will depend on the size of the empanadas and your oven.