Chicken With Grape Mustard Cream

• 1 1/2 seedless green california
• 1 grapes
• 120 ml dry wine (white)
• 85 gr mushrooms (sliced fresh)
• 60 ml cream (heavy)
• 28 gr butter
• 16 ml dijon-style mustard
• 12 gr onion (minced)
• 8 gr flour
• 1 gr marjoram (dried)