Season the chicken pieces well with salt and pepper.
Select “Manual” on the Cook4Me+ and choose the “Browning” function. Once the pot has reached temperature, fry the chicken pieces in batches until golden brown. Add mushrooms
Pour in the champagne to deglaze the pot. Fry for 2 minutes. Add the chicken stock.
Select “Pressure Cook” on the Cook4Me+ and adjust time to 20 minutes. Once chicken is cooked, remove it and the mushrooms from pot and place on platter.
Whisk together the crème fraiche, seeded mustard and tarragon and return to pot.
Select “Browning” function and whisk the cream and mustard into the chicken juices until it reduces slightly. Pour this creamy sauce over the chicken and garnish with more tarragon.