Preheat oven to 350 degrees F.
1) Whisk together ingredients (except melted butter) in a medium bowl. It should be a very thin batter. Let sit for at least 15 minutes. Then stir in melted, but cool, butter.
2) Add a small dab of butter to a large nonstick skillet and swirl around over medium heat until melted.
3) Pour in about 1/3 cup of batter to the pan and immediately swirl the batter around to spread it around the pan in a thin layer. Cook for about 90 seconds on that side.
4) Flip crepe carefully with a thin spatula and cook for another 15 seconds on the second side until it’s lightly browned.
5) Cook all the crepes and stack them up.
To make a crepe box:
1) Place a crepe on a baking sheet (it’s fairly hard to transfer after shaping it).
2) Sprinkle some grated cheese in the center of a crepe and hollow out the center a bit. Lay some ham on the crepe but leave some room in the center for the egg.
3) Crack an egg in the center and then carefully roll the edges of the crepe up to form sides of a box. You will have to kind of press the crepe edges down to keep them in place.
4) You should be able to fit 2-3 boxes on a baking sheet. Bake the crepe box until the egg is just firm, but still a bit runny in the yolk, about 15-18 minutes. When it comes out, season with a pinch of salt and pepper and serve immediately.
For the sweet version, slice apples thinly. Smear the crepe with a few tablespoons of cream cheese and top with sliced apples. Sprinkle with cinnamon and sugar and roll crepe edges up to form a box. Bake just like the savory version (15-18 minutes).