In large skillet over high heat melt butter, add onions (a little salt), fry until soften (2 min), add flour and stir continuously for around 5 min to get rid of any lumps (it will have small bubbles). Add Chicken broth stir until boiling, then add cream (or milk), and stir until boiling. Let cook until it thickens a little. (Or how think you like it). Add mushrooms and mix vegetables, and paprika. Let cook until boiling, keep stirring, and add chicken. Lower to a medium heat and heat until chicken is hot.