Ingredients :

1 1/2 - 2 pounds frozen cut green beans (use fresh trimmed green beans when in season)

2 Tbs unsalted butter

10 oz sliced baby bella (the little portobella) mushrooms (see variation below)

3 Tbs minced shallots (if shallots are not available, finely diced onion works well)

1/4 cup all purpose flour