Chicken Rolls stuffed with Spinach - My favorite

This is my favorite chicken my mom makes.
Six Servings. (Freeze for later). Approx. cost $3.00 per serving.

1 lb fresh spinach
1/2 lb fresh mushrooms
8 very thick slices Prosciutto or boiled Ham
3 T butter
1 C. finely chopped onion
2 small cloves garlic, finely minced
1 C cold cooked rice
Salt and pepper to taste
3 whole, skinless, boneless chicken breasts, about 1.5 lbs
Flour for dredging
1/3 C. finely diced carrot
1/4 C. finely diced celery
1/4 C. dry white wine
1/2 C chicken broth
Sprig of fresh thyme, or 1/2 t dried thyme
1 Bay leaf

Preheat oven to 375 degees.
Wash spinach and boil for 1 minute. Drain immediately.
When spinach is cooled, extract excess liquid. Chop spinach finely with a knife and set aside.
Chope mushrooms. Set aside. Should be 1 3/4 cups.

Cut 2 of the prosciutto slices into thin strips. Chop finely. Set aside.

Heat 1 T of butter in skillet and add half the onion, 1 clove o garlic and 1/2 C. of diced mushrooms.
Cook 3 minutes and dd chopped prosciutto. Stir in the spinach and rice. Sprinkle salt & pepper. Stir and then set aside.

Split each chiken breast in half. Trim away and discard the carilege and nerve tissues. Place the chicken breast halves skinned side down on a flat surface and pound lightly with the bottom of a clean skillet. Spoon equal amounts of filling down the center of each chicken breast half. Roll the end of the chicken over to enclose the filling and tuck in the bottom and top. Tie each bundle in two places with string.

Dredge each bundle in flour seasoned with salt and pepper.

Heat the remaining 2 T. of butter in large skillet and brown the chicken for 10 minutes.

Remove the chicken pieces and add the remaining onion, mushrooms, and garlic.
Cook briefly and add the carrots and celery.
Sprinkle with 2 T. flour and add the wine, stirring with a wire whisk.
Cook 5 minutes and add the broth. Stir and add the thyme and bay leaf.
Return the chicken rolls to the skillet. Cover with a round of wax paper and place in the oven.
Bake 30-40 minutes until tender.

Remove the chicken rolls and discard the strings. Serve hot with sauce spooned over.