Preheat oven to 400*F. Lightly grease a baking sheet and set aside.
Place Brazil nuts in a food processor and pulse until finely ground. Transfer to a small bowl and stir in breadcrumbs and Parmesan cheese.
Place tilapia fillets on baking sheet and spread evenly with mustard. Divide Brazil nut mixture evenly over tilapia and lightly spray breadcrumbs with cooking spray. Bake 8 to 10 minutes, or until tilapia is just cooked through.