01 - Whisk flour and salt in a large bowl. Create a well in center, add eggs, then gradually whisk in milk and melted butter until smooth. Let batter rest 10 minutes.
02 - Heat a nonstick crepe pan over medium heat, lightly buttered. Pour 1/4 cup batter, swirling to coat bottom thinly. Cook 1-2 minutes until edges lift and bottom golden. Flip 30 seconds. Transfer to plate. Repeat with remaining batter.
03 - Preheat oven to 350°F.
04 - Layer ham slices (if using), spinach, cheese, and crème fraîche on each crepe. Season with black pepper. Fold into quarters or roll up.
05 - Arrange crepes in baking dish, sprinkle remaining cheese on top. Bake 8-10 minutes until cheese melts and crepes heated through.
06 - Serve hot, garnished with fresh spinach or paired with side salad if desired.