In a blender or large bowl using an electric mixer, combine the eggs, milk, flour, oil (or butter) and salt. Blend or mix on high until the ingredients are well combined. Cover the batter and chill in the refrigerator at least 1 hour or up to 24 hours. This helps the gluten to relax, making the crepes even more tender.
When ready to start cooking the crepes, heat a 10-inch nonstick skillet over medium heat for 2-3 minutes. Spray the bottom and sides of the skillet with nonstick cooking spray. The skillet should sizzle like crazy. You want it piping hot before you pour in the crepe batter.
Quickly whisk the crepe batter to recombine, then measure out 1/4 cup of the batter. Tilt the skillet off the heat and pour the batter to one side of the skillet, immediately twirling the skillet to coat the bottom with the batter. Set the skillet back on the heat and cook the crepe until the edges begin to brown, about 1 minute. Loosen the crepe around the edge with a heat-proof spatula and gently (but quickly!) pick up the edges of the hot crepe with your fingers and give it a fast flip.
Cook the other side for 30 seconds or so until lightly golden brown and cooked through. Transfer the crepe to a wire rack. The key is to keep the skillet sizzling hot without burning the crepes - I moderated the heat of my stovetop between medium and slightly above that to keep the crepes cooking quickly without burning. You should hear an audible sizzle when you pour the crepe batter into the skillet but if you hear a sizzle with accompanying smoke - the skillet is probably too hot.
Repeat with remaining batter (spraying the skillet with cooking spray every 2-3 crepes), stacking the crepes as they finish cooking. The crepes can be placed on a baking sheet and lightly covered with foil and placed in a 200 degree oven to stay warm for 20-30 minutes while you finish cooking the remaining crepes.
Serve the crepes with your favorite toppings. Some of ours include nutella and strawberries, butter and cinnamon and sugar, maple or other fruit syrup. To store leftover crepes (or to make in advance): once the crepes have cooled, stack them between pieces of parchment or wax paper. Wrap the stack of crepes in plastic and store them in a resealable plastic bag in the refrigerator for several days or for up to 2 months in the freezer. Completely thaw frozen crepes before carefully pulling them apart.
Chilling the Batter: if you are going to let the batter chill out and rest in the refrigerator longer than 1-2 hours, I'd recommend using the oil option instead of the butter, as the butter likes to solidify into mini clumps if refrigerated longer than a couple of hours. Ham, Asparagus and Swiss Cheese Crepes Variation: In a medium bowl, toss together 8 ounces chopped, cooked ham, 1 1/2 cups shredded swiss cheese, pinch of black pepper. Spoon 1/4 cup of ham/cheese mixture down the center of each crepe and top with 2 asparagus spears, cut in half (so you'll have four pieces of asparagus per crepe). Roll up enchilada-style. Arrange the crepes seam-side down on a lightly greased baking sheet. Bake the crepes at 400 degrees for 10-12 minutes, until the cheese has melted and the crepes are golden brown. While the crepes are baking, melt 4 tablespoons butter in a medium saucepan. Whisk in 1/4 cup all-purpose flour and cook for 1-2 minutes, stirring constantly. Slowly whisk in 1 cup low-sodium chicken broth and 1 cup lowfat milk until the mixture is smooth. Bring the mixture to a low boil, stirring often, and simmer for 3-4 minutes, until thickened. Whisk in 2 tablespoons stone-ground mustard (use more according to taste) and add salt and pepper to taste. Serve the warm ham/asparagus crepes topped with the sauce.