Thinly slice the bottoms of spring onions to make 2 C. Finely mince the greens and keep separate.
Thinly slice 1 fennel bulb.
Saute the fennel and onions over medium heat with 2 T. olive oil or butter. Sprinkle with salt and pepper. Cook until they are lightly browned, then drizzle with 1 T. lemon juice and turn off the heat.
Heat a crepe pan or 8 inch cast iron skillet. Coat the pan lightly with butter using a paper towel. Add 1/4 C. crepe batter and cook until lightly browned on one side — about two minutes — and then quickly flip and cook the other side. Remove the crepe to a plate. Stack the other crepes on top as you cook them.
Trim 1 bunch of asparagus, then toss with 1 t. olive oil and salt. Grill until tender. (Alternately, you can steam or boil the asparagus until just tender).
Heat the oven to 400 degrees. Assemble the crepes by spreading a thin layer of the onion/fennel mixture on one half and topping it with 3 asparagus spears. Sprinkle the whole thing generously with grated Gruyere cheese, then fold over and place in a single layer on a cookie sheet.
Bake for 5-7 minutes and serve sprinkled with the spring onion “chives”.