TO MAKE THE SAUCE
Put a skillet on medium heat and add 1 tbsp of the butter. When the butter is melted throw in the diced shallots and garlic. Saute till tender.
Add the white wine and reduce it till there's about a 1/4 of a cup of liquid in the pan, then add the rest of the butter. When its melted, add the flour and cook for a minute stiring with a whisk.
Add milk and chicken broth and cook till it thickens. Spoon in the mustard and stir to combine.
Sprinkle in the greyere cheese.
Season with salt and pepper to taste.
FOR THE MUSTARD BUTTER
Melt the butter and place in a small bowl.
Add the rest of the ingredients and stir to combine.
FOR THE SHREDDED CHICKEN
Season the chicken with salt and pepper on both sides.
Heat a skillet on medium high heat. Once its hot, add the oil to the pan and brown the chicken on both sides.
Add the garlic and the broth and throw it in the oven at 300 degrees for 1 hour.
Once its done, shred the chicken with two forks, remove from the skillet and set aside for a moment.
On the stove, heat the skillet on medium heat and add the onion and proscuitto or bacon. Saute till the onions and bacon are cooked.
Add the zucchini and garlic. Saute for another min or so then add the chicken back to the pan. Stir to combine and remove from the heat.
TO MAKE THE STUFFED MUSHROOMS
Pre-heat the oven to 350 degrees and line a baking sheet with parchment paper.
Paint the inside of the portobello mushrooms with the Maille Parmesan and Bail Mustard sauce and place them on the baking sheet.
Bake them in the oven for about 5 mins. Take them out and stuff with the chicken mixture, and then bake again for anther 5 mins or until they are fully heated.
Remove them from the oven, plate them and then drizzle the sauce on top.
Sprinkle with chives and serve immediately.