Instructions: Preheat oven to 375 degrees. Oil a 9-by-13 inch baking dish or ovenproof casserole.

Toast bread in oven until golden, 4 to 5 minutes, and allow to cool. Break into chunks, chop into crumbs in a food processor and mix with grana padano. Set aside.

In a large saute pan over medium heat, heat 4 tablespoons canola oil until very hot, and saute mushrooms until fully cooked, about 5 minutes, stirring often. Remove from heat and place in a strainer to drain and cool.

Bring 6 quarts of salted water to a boil with 4 tablespoons canola oil. Add pasta and cook, stirring occasionally to prevent sticking, until al dente, 8 to 10 minutes. Drain and reserve.

In a large saucepan over medium heat, heat remaining 8 tablespoons canola oil until moderately hot and whisk in flour. Cook, whisking constantly, until lightly golden brown, about 5 minutes. Raise heat and slowly whisk in milk; cook, whisking, until it comes to a boil. Whisk in cheddar until well blended.

Add salt, pepper and mustard, and cook, stirring constantly until mixture thickens - it will get quite thick (it starts to thicken as soon as you add the milk, so this part takes only a few minutes). Remove from heat, add ziti and mushrooms, and stir until well coated.

Pour macaroni mixture into prepared baking dish and top with bread crumb mixture. Bake on middle shelf until bubbling and top is golden, about 20 minutes.

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