Preheat the oven to 425-degrees. Blanch the vegetables in boiling salted water, rinse in cold water and drain well. Boil the pasta according to package directions. Take care not to overcook the veggies or the pasta, they will cook more in the oven.
Meanwhile, heat 1-tablespoon butter and 2 tablespoons olive oil in a heavy pot over medium heat. Sprinkle in the flour and blend with a wooden spoon to work out all the lumps. Simmer the roux for several minutes, add the onions and salt and continue to simmer. When the onions are tender, turn off the heat and blend in the mustard, paprika and bay leaf and pepper.
Slowly whisk in the milk just a little at a time. Add a pinch of sugar and bring to a boil over medium high heat, stirring almost constantly reduce heat and simmer until the sauce has thickened, about 10 minutes. Melt in the cheese one handful at a time, taste and adjust. Remove from heat and temper in beaten egg, whisking constantly.
Combine the pasta, veggies and sauce and transfer into one or more oiled ceramic crocks. Toss breadcrumbs in 2 TBS olive oil and 1 TBS melted butter and sprinkle over the casseroles. Roast in the top of a 425-degree oven until browned and bubbling.
