Heat the oven to 400° F. Lightly oil a 9-inch square baking dish, or another baking vessel of your choice. Fill a large pasta pot with salted water and bring to a boil.
In a medium saucepan, bring the stock and milk to boil. Meanwhile, in a mixing bowl combine the flour, butter, cheddar, ricotta, and 2 tablespoons of the Parmesan. When the stock and milk begin to boil, slowly whisk in the cheese mixture. Reduce to a simmer and cook, stirring often, until slightly thickened, about 10 minutes. Remove from the heat.
When the pasta pot boils, add the macaroni and cook until just al dente. Then add the broccoli and cook everything for a minute more. Drain.
In a large bowl, mix the macaroni and broccoli with the cheese sauce. Transfer it all to the baking dish and top with bread crumbs and the rest of the Parmesan. Drizzle with olive oil. Cover with aluminum foil and bake for 20 minutes, then remove the foil and bake for another 5 to 10 minutes, or until crisp and golden on top.