Brussels Sprout Casserole

Bahan-bahan (8 porsi)

• 2 pounds Brussels sprouts (halved lengthwise, quartered if large)
• 1 tablespoon olive oil
• 6 slices bacon (chopped)
• 2 tablespoons all-purpose flour
• 1¾ cups whole milk
• 1½ cups shredded gruyere cheese (or sharp cheddar)
• ½ teaspoon onion powder
• ¼ teaspoon salt (more to taste)
• ¼ teaspoon black pepper
• 10 Ritz Crackers (crushed)
• ¼ cup shredded Parmesan cheese
• 1 tablespoon salted butter (melted)