Whisk the flour, eggs, and milk together in a large bowl until smooth. Let the batter rest for 20–30 minutes.

Heat a non-stick frying pan over medium heat with a little oil. Pour in just enough batter to coat the base of the pan in a thin layer. Cook for 1–2 minutes until the edges lift easily, then flip and cook for another 1 minute. Repeat with the remaining batter.

Place a slice of ham and a sprinkle of cheese on one half of each crêpe. Fold the crêpe over and press gently to seal.

In the same pan, cook the filled crêpes over medium heat until the cheese melts and the crêpe is golden and crisp. Slice in half and serve warm.