The ballotines:
Remove the sausage casings.
Mix the sausage meat, pistachios, thyme, and sage.
Open the chicken breasts like a book and fill with the meat mixture.
On a sheet of aluminum foil, brush with oil and lay out 4 slices of bacon.
Place a chicken breast on the bacon and fold the bacon slices over the top of each breast, crossing them.
Roll the aluminum foil around the ballotine, tightening it, and twist the ends to form a “bonbon”.

Place the ballotines in boiling water for about 25 minutes.
Remove the ballotines from the water and remove the aluminum foil.
In a pan, add a little oil and cook the ballotines on all sides until the bacon is golden and crispy.
Cut the ballotines into slices (about 4-5 per ballotine). Set aside and keep warm.

Forest sauce:
Soak the dried mushrooms in boiling water. Let it steep for 15 minutes.
Remove the mushrooms from the water (and reserve it), then slice them.

In a pan, cook the white and wild mushrooms in a little butter with the shallots.
Add the sliced bacon and cook until it’s golden.

Sprinkle the mixture with flour and mix well to coat.
Deglaze with white wine, stirring constantly, then add the mushroom soaking water and mix well.
Add the thyme and rosemary sprigs. Season to taste, then simmer uncovered for 10 minutes, stirring occasionally, to prevent it from sticking to the bottom of the pan.

To serve, remove the thyme and rosemary sprigs and spoon the forest sauce over the ballotine slices.