• 2 tablespoons butter
• 2 tablespoons all-purpose flour
• 1 cup sour cream
• ¼ cup diced onion
• 1 teaspoon salt
• 1 teaspoon white sugar
• 3 (14.5 ounce) cans French-style green beans, drained

Topping:

• 2 cups shredded Cheddar cheese
• ½ cup crumbled buttery round crackers
• 1 tablespoon butter, melted

1. Preheat the oven to 350 degrees F (175 degrees C).
2. Make green beans: Melt butter in a large skillet over medium heat. Stir in flour until smooth, and cook for 1 minute. Stir in sour cream, onion, salt, and sugar. Add green beans, and stir to coat. Transfer mixture to a 2 1/2-quart casserole dish.
3. Spread Cheddar cheese over green bean mixture. Toss cracker crumbs and melted butter together in a small bowl; sprinkle over bean mixture.
4. Bake in the preheated oven until topping is golden and cheese is bubbly, about 30 minutes.