In a large mixing bowl, whisk together flour and sea salt. Create a well and add eggs, gradually incorporating milk. Stir in melted butter until smooth. Cover and let rest for 30 minutes.

Preheat your nonstick skillet over medium heat. Brush with melted butter. Pour approximately 60 ml of batter, swirl to coat. Cook for 1-2 minutes until edges lift, flip and cook for 30 seconds. Repeat.

Spread a layer of Dijon mustard on each crêpe, layer with ham, and sprinkle Gruyère cheese. Fold into a triangle, encasing the filling.

Return crêpes to skillet over medium heat. Cook for 1-2 minutes each side until cheese melts and edges are crispy.

Remove from skillet, garnish with parsley and black pepper. Serve immediately.