Heat 1 Tbsp. oil in large saucepan over medium-high heat. Add onion, garlic and red pepper flakes. Cook 3-5 minutes, stirring occasionally, until onions soften. Add broth and tomatoes. Simmer 5-7 minutes, or until heated through.
Meanwhile, preheat oven to 250°F.
Add bread to a baking sheet. Drizzle with 1 Tbsp. oil, garlic powder and salt. Toss to coat.
Bake 10-15 minutes, stirring occasionally, until toasted on all sides.
Divide soup into 4 bowls. Top with croutons, basil and cheese.