1. Preheat the oven to 180°C.

2. Season the inside of the guinea fowl with salt and pepper. Cover the guinea fowl with butter and place it in a baking dish with 100 ml of sweet wine. Cook for 45 minutes, basting frequently with cooking juices.

3. Peel the asparagus and cook in boiling salted water for 6 minutes; drain. Let cool on a cloth and cut into segments.

4. In a skillet, brown the lardons with extra virgin olive oil over high heat. Add the asparagus, reduce the heat, and cook for 4 minutes.

5. Remove the guinea fowl from the oven and reserve, covered with aluminum foil to keep warm.

6. Deglaze the baking dish, pour in the dry white wine, and bring to a boil, scraping the bottom of the pan. Add the chicken broth and cook for 3 minutes. Season with salt and pepper.

7. Carve the guinea fowl and place the pieces on warm plates. Sprinkle with fleur de sel and pepper.

8. Arrange the asparagus around the guinea fowl; drizzle with a little cooking juice. Pour the rest into a gravy boat. Garnish with chervil and serve immediately.