Grandma's Green Bean Casserole

We tried this recipe for Thanksgiving.  It was a great side dish.  We both like this recipe.  I especially liked that it had a homemade cream sauce instead of a canned soup.  We are both used to the normal Green Bean Casserole and I think just for tradition sake we will make that one for next Thanksgiving but this one will go in our rotation for a side dish on normal days.

Grandma's Green Bean Casserole
from allrecipes

Ingredients:
2 TBS butter
2 TBS all-purpose flour
1 tsp salt
1 tsp white sugar
1/4 cup onion, diced
1 cup sour cream
3 (14.5 once) cans French style green beans, drained
2 cups shredded Cheddar cheese
1/2 cup crumbled buttery rounds crackers 
1 TBS butter, melted
(I also added some chopped fresh mushrooms and instead of the ritz, I put french fried onions on top)

Directions:
Preheat oven to 350 degrees F.  Melt 2 TBS butter in a large skillet over medium heat.   Stir in flour until smooth and cook for one minute.  Stir in the salt, sugar, onion, and sour cream.  Add green bean, and stir to coat.

Transfer the mixture to a 2 1/2 quart casserole dish.  Spread shredded cheese over the top.  In a small bowl, toss together cracker crumbs and remaining butter, and sprinkle over the cheese.

Bake for 30 minutes in the preheated oven, or until the top is golden and cheese is bubbly.  

(I did not follow the instructions for the cheese.  Some of the reviews said the cheese was crispy on top so instead, I mixed the cheese into the cream mixture and cooked it that way).