Trim broccoli, reserving stems for another use, and cut florets into 1-inch pieces. (There should be about 5 cups.)
Trim cauliflower and cut florets into 1-inch pieces. (There should be about 5 cups.)
In a large saucepan of boiling salted water cook vegetables until crisp-tender, 2 to 5 minutes. In a colander drain vegetables and refresh under cold water to stop cooking. Drain vegetables well. Vegetables may be prepared up to this point 1 day ahead and chilled, covered.
In a large heavy skillet heat oil and 2 tablespoons butter over moderately high heat until foam begins to subside and saute bread crumbs, stirring, until golden. Stir in Parmesan, cayenne and salt to taste and saute, stirring, until crisp. Bread crumbs may be prepared 3 days ahead and kept in an airtight container.
Preheat oven to 350 degrees F.
In skillet melt remaining tablespoon butter over moderate heat and in it toss vegetables with salt and pepper to taste. Sprinkle vegetables with bread crumbs and toss to combine. Transfer mixture to a baking dish and bake, uncovered, 10 minutes, or until just heated through.