Blend together your chestnut flour, milk, salt (if using), and eggs in a large bowl until fully smooth (about 1 minute). If you don't have a hand mixer, you can also use a fork and then a powerful milk frother to blend everything thoroughly.
Take out a large, flat pan and put it over your largest burner (don't use a cast iron pan). Turn the heat on medium-low and use a balled-up paper towel to smear enough oil onto your pan to coat it thoroughly, and let it heat for one minute.
Once the pan is hot, hold the bowl of batter in your non-dominant hand, and using your dominant hand, ladle about ¼ cup of batter into the center of the pan, making a circle. If your batter turns out very thin, you can also try to make crepes the traditional way. This involves immediately tilting the pan in a circular motion to spread the batter in a thin circle; the thinner, the better, but don't leave it patchy. Not all attempts will be winners, but you don't need a perfect circle to make a great-tasting chestnut crepe. If your fourth try is still as bad as your first, try pulling your pan off the heat and then adding more oil, letting it cool for a minute or so, and then adding the batter before the swish and flick. Either way, cook the crepe for 2-3 minutes, then flip it as soon as the bottom is set. You'll know it's set once the edges begin to turn golden and the top is no longer glossy.
Use your spatula to lift the edges of the crepe, doing this slowly to make sure it hasn't stuck to the pan. Grab your biggest spatula and very gently work it under the crepe, gingerly also using your fingers to flip it over quickly, if needed. Cook the other side for another minute or until just barely done. Don't overcook it or it will dry out.
Butter the pan again and repeat the process for each successive crepe, remembering to keep buttering the pan in between or the crepes will stick. Add any fillings to your crepes when they're hot, then fold them, flip them over, add final toppings, and enjoy.