Cut the mushrooms into slices.
Melt butter in large frying pan. Add in onions, garlic, and mushrooms. Cook until onions are soft.
Blend in 2 T. flour and stir.
Add in the chicken broth and heat until slightly thickened while stirring frequently.
Stir cream with additional 1 T. flour and seasonings. Add in cream to soup. Heat to thicken while stirring frequently.