<b> For the Homemade French Fried Onions </b>
In a medium bowl, toss onion, flour, breadcrumbs, and salt and pepper.
In a large skillet, heat ~1/2 inch of oil. Add onions a little at a time. Fry until golden brown.
Drain on paper towels. Set aside.
<b> For the Green Beans </b>
In a large stock pot,boil green beans in salted water for ~5 minutes. Drain and put into an ice bath. Set aside.
<b> For the Homemade Mushroom Cream Sauce </b>
In a large skillet, melt butter over medium high heat. Add in mushrooms, salt, and pepper. Cook for 3-5 minutes.
Stir in garlic, and cook for ~1 more minute. Stir in flour.
Stir in broth a little at a time, stirring constantly. Simmer for 1 minutes. Add cream.
Cook for 5-7 more minutes or until thickened.
<b> For the Green Bean Casserole From Scratch: Putting It All Together </b>
Stir cooked green beans into the sauce until well coated. Top with french fried onions.
Bake for 15-20 minutes or until bubbling.