1
Blend the sour cream and heavy cream together in a glass jar. Cover and let stand at room temperature until just before serving time.
2
In the crock of a slow-cooker, stir together the butter spread, mushrooms, leeks, wine, 1 Tbs. of Mustard, thyme, celery salt, and pepper.
3
Add the chicken pieces to the crock and mix all ingredients together. Cover and cook on low for 7-8 hours or high for4-5 hours until chicken is cooked through and fork tender.
4
Leaving the sauce in the crock, remove chicken and keep warm.
5
Remove 1/4 - 1/2 cup of the sauce and reserve for another use.
6
Whisk the sour cream/heavy cream mixture and the remaining mustard into the crock. Season to taste.
7
If sauce is too thick, thin as desired with reserved sauce.
8
Replace chicken into crock and stir to coat.
