Using a blender or immersion blender, whiz together the 4 eggs, 1 ¾ cups of whole milk and salt until everything has blended, about 10 seconds. Add in the flour and whiz until the batter is smooth, about 20 seconds. Pour in the unsalted butter and whiz until combined, about 10 seconds.
Transfer the batter into a large bowl, with an opening sized so that you can easily use a ¼ cup measuring cup to scoop up the batter. Allow the batter to sit for at least 5 minutes, but up to 24 hours. If resting the batter longer than 30 minutes, cover and transfer the easy crepe batter to the refrigerator.
When you are ready to make these easy basic crepes, remove the batter from the refrigerator and allow to sit for at least 10 minutes. Check the consistency of the batter. It should be the consistency of heavy cream. If the crepe batter feels too thick, whisk in additional milk by the tablespoon, up to ½ cup more.
Preheat a 10 or 12-inch skillet or crepe pan on medium to medium-high heat (I fluctuate between 6/9 and 7/9 on my stove setting). In a small bowl, melt about 2 tablespoons of butter. When the pan is hot, using a small silicone brush, brush on a thin layer of butter. Alternatively, melt and swirl the butter around the pan.
Scoop on ¼ of the basic crepe batter in the center of the pan. Quickly, using a crepe spreader, evenly spread the batter in a circular motion until the crepe is thin and the batter has reached the edge of the pan. You can also quickly swirl the pan around so the crepe batter spreads into a thin layer, but I don't always have success getting perfectly round crepes this way.
Cook the crepe until the edges begin to dry and lift from the sides of the pan, and the bottom is golden brown, about 1 minute. Gently flip the crepe over using a spatula and smooth out any folds. Cook for an additional 20-30 seconds. Slide the crepe off the pan onto a plate to serve, or to a cooling rack if you are making more. You can stack on the crepes as they finish cooking.
Repeat with remaining crepes, brushing butter on the pan each time before you pour on the crepe batter.
These basic crepes are delicious served straight off the pan. However, if you plan to store the crepes, you can refrigerate them in as a stack and slowly peel off each crepe as you want to eat it. You can also freeze them with a layer of parchment paper in between, so they do not stick together frozen. Gently heat the crepes on a pan before serving.
The amount of milk varies because of the exact size of your egg and the exact amount of flour you use. To store: If you plan to store these easy basic crepes, you can refrigerate them in as a stack and slowly peel off each crepe as you want to eat it. You can also freeze them with a layer of parchment paper in between, so they do not stick together frozen. Gently heat the crepes on a pan before serving.