Lynn's Recipes - Fresh Broccoli Casserole

Ingredients

• ¼ stick butter
• ¼ cup flour
• ¼ teaspoon kosher salt
• ¼ teaspoon black pepper
• 1/8 teaspoon garlic powder
• 1/8 teaspoon onion powder
• 1 cup milk
• 1 head fresh broccoli, chopped
• ¼ cup onion, diced
• ½ cup mayonnaise
• ¼ cup milk
• 1 cup shredded cheddar cheese
• 1 egg, beaten
• 1 cups panko crumbs
• Additional melted butter to drizzle on top of panko crumbs