Baked Parmesan Broccoli

I LOVE broccoli and was excited to try this new way to make it. It was very good and I'm sure it's even better with the bread crumbs on top giving it some crunch! (recipe from taste of home magazine)

* 4 bunches broccoli, cut into florets
* 6 tablespoons butter, divided
* 1 small onion, finely chopped
* 1 garlic clove, minced
* 1/4 cup all-purpose flour (I used cornstarch)
* 2 cups 2% milk
* 1 egg yolk, beaten
* 1 cup grated Parmesan cheese
* 1/2 teaspoon salt
* 1/8 teaspoon pepper
* 1/2 cup seasoned bread crumbs (I left off to keep it gluten-free)

* Place half of broccoli in a steamer basket; place in a large saucepan over 1 in. of water. Bring to a boil; cover and steam for 3-4 minutes or until crisp-tender. Place in a greased 13-in. x 9-in. baking dish; repeat with remaining broccoli.
* Meanwhile, in a small saucepan over medium heat, melt 4 tablespoons butter. Add onion; cook and stir until tender. Add garlic; cook 1 minute longer.
* Stir in flour until blended; gradually add milk. Bring to a boil; cook and stir for 2 minutes or until thickened. Stir a small amount of hot mixture into egg yolk; return all to the pan, stirring constantly. Cook and stir 1 minute longer. Remove from the heat; stir in the cheese, salt and pepper.
* Pour over broccoli. In a small skillet, cook bread crumbs in remaining butter until golden brown; sprinkle over the top.
* Bake, uncovered, at 400° for 15-18 minutes or until heated through. Yield: 12 servings (3/4 cup each).