Broccoli, Cheese, and Rice Cassarole

2 slices hearty white sandwich bread, torn into pieces
3/4 cup grated parmesan cheese
4 tablespoons butter, melted; plus two tablespoons chilled
1 garlic clove, minced
2 pounds broccoli (about 3-4 medium heads of broccoli), florets cut into 1-inch pieces, stems chopped
1 onion, finely chopped
1 1/4 cups long grain white rice
4 cups low-sodium chicken broth
1 1/4 cups half-and-half
1 teaspoon salt
2 cups shredded extra-sharp cheddar cheese
1/8 teaspoon cayenne pepper

Preheat the oven to 400 degrees. Grease a 9X13-inch baking dish. Pulse bread, 1/4 cup parmesan cheese and melted butter, and garlic in a food processor until coarsely ground, set aside. Microwave broccoli florets (save stems for later), covered, in a large bowl until bright green and tender, 2 to 3 minutes (no need to add water). Be careful not to overcook or they will become soggy and discolored. Melt remaining butter in a large pot over medium heat. Cook onion and broccoli stems until softened, 8 to 10 minutes. Add rice and cook, stirring constantly, until rice is translucent, about 1 minute. Stir in broth, half-and-half, and salt and bring to a boil. Reduce heat to medium-low and cook, stirring often, until rice is tender, 20 to 25 minutes. Turn off the heat, stir in cheddar cheese, cayenne, remaining parmesan and broccoli florets.Pour the mixture into prepared baking dish and top with bread crumb mixture. Bake until the sauce is bubbling around the edges and the top is golden brown, about 15 minutes. Cool 5 minutes. Serve.