Lightly spoon flour into a dry measuring cup; level with a knife. Place in a medium saucepan; gradually add milk, stirring with a whisk until blended. Stir in minced garlic. Place over medium heat, and cook until thick (for about 5 minutes); stir constantly. Stir in fontina and next 6 ingredients (fontina through garlic powder), and cook 1 minute. Stir constantly until cheese melts.
Bring water to a boil. Add pasta; cook 6 minutes. Add broccoli and carrot; cook 6 minutes. Stir in bell pepper and peas; cook 1 minute. Drain. Combine pasta mixture and cheese mixture. Serve immediately.