Preheat oven to 400 degrees

Butter a round casserole dish. In the past I used a 10" silicone one, but I have also used a cast iron skillet, a clear glass pie pan, as well as a round casserole dish. Could also be done in a square pan. It just needs to hold liquid.

Bring a medium pot of salted water to a boil and prepare a bowl with ice water. Blanch the asparagus slivers for 2 – 3 minutes, or until bright green and still crisp. Drain and plunge into the ice water to stop the cooking. Drain again and pat dry with paper towel.

Combine milk, eggs, salt and pepper in mixing bowl and whisk thoroughly.

Spread Dijon mustard on the bottom half of the croissant and dip into the egg mixture being sure to thoroughly saturate.Tear the croissant into pieces putting the bottom outside of the croissant on the bottom of the casserole dish. Continue with all the remaining bottom halves in the same manner. Once the bottom is fully covered, press the pieces down lightly to ensure good contact with the bottom of the dish

Place the asparagus, chiffonade of sage, thyme, and cheese on top of the bottom croissants.

Take the top of the croissants and again spread with a thin layer of Dijon mustard and dip into the egg mixture being sure to saturate the piece.Tear the croissant into pieces and put the top outside of the croissant face up on the filling.Continue with the remaining croissant halves. Once the top if fully covered, press the pieces down lightly to ensure good contact with the filling.

Pour the remainder of the egg mixture over the top of the dish and allow to soak in for about 3 – 5 minutes before placing in oven. You can also decorate the top at this point with reserved sage leaves.

Place in oven and bake for about 25 – 35 minutes or until browned on the outside and cooked but still slightly custardy in the middle. You can slice into servings in the pan, or you can remove from pan. I find using a bread knife or serrated knife to slice works easiest.