Bake the croutons a day or two in advance; store at room temperature in a zip-top plastic bag. Make and refrigerate the vinaigrette a day ahead; reheat gently over low heat before tossing with the greens.
To prepare croutons, arrange bread cubes on a baking sheet. Lightly coat bread cubes with cooking spray. Sprinkle evenly with lemon pepper and garlic powder; toss to coat. Bake at 350° for 10 minutes or until crisp, stirring once.
To prepare salad, combine arugula, radicchio, and escarole in a large bowl.
To prepare vinaigrette, heat oil in a nonstick skillet over medium heat. Add shallots and garlic; cook 5 minutes, stirring occasionally. Add tomato; cook 2 minutes, stirring frequently. Stir in vinegar, sugar, mustard, salt, and black pepper. Reduce heat to low; cook 2 minutes or until warm. Drizzle warm vinaigrette over salad; toss gently to coat. Place 1 cup salad on each of 9 salad plates; top each serving with about 2 1/2 teaspoons cheese. Divide croutons evenly among salads.