Homemade Green Bean Casserole

Canned soup is so 50 years ago. Make your own!

1 1/2 lbs slender green beans, trimmed, cut into 1" lengths
1 1/2 Tbsp unsalted butter
1 cup onion, chopped small
10 oz cremini mushrooms, halved and sliced (to taste)
3 Tbsp butter
1/4 c flour
2 c milk
Salt and pepper
3 shallots, sliced
Flour
Butter

Steam green beans until tender. Drain and set aside.

While green beans steam, in a large skillet over medium heat, cook onion in butter until beginning to soften, about 4 minutes. Add mushrooms; cook another 8 minutes or until mushrooms have given up their juice and juice has largely cooked off. Season with salt and pepper. Remove from saucepan and set aside.

In same saucepan over medium-low heat, melt butter. Add flour, whisking constantly, until mixture turns light golden, about 2 minutes. Stir in milk, whisking until mixture has thickened, about 3 minutes. Season with salt and pepper. Stir in mushroom mixture, then green beans.

Butter a 9"x13" casserole dish. Spread green bean mixture evenly in dish. (Casserole can be held at this point in refrigerator, covered, 2 days.) Bake until dish is heated through and bubbly.

While dish bakes, toss shallots in flour, then fry in butter until crisp. Remove dish from oven and sprinkle with fried shallots. Serve.