Heat oven to 375°F. Spray 3-quart casserole with cooking spray. Cook and drain pasta as directed on package, using minimum cook time.
Meanwhile, in 1-quart saucepan, melt 1/4 cup butter over medium-low heat. Stir in flour, salt and pepper. Cook and stir until smooth and bubbly. Gradually add milk, stirring constantly, until sauce boils and thickens. Stir in fontina cheese. Remove from heat.
In large bowl, toss pasta, cauliflower, tomatoes and chiles. Pour sauce over mixture; toss to mix. Spoon into casserole. In small bowl, mix topping ingredients. Sprinkle over top.
Bake uncovered 20 to 30 minutes or until topping is golden brown.