Add oil and vinegar slowly through feed tube and blend until smooth. Season with salt and pepper. Combine spinach and basil in salad bowl. Place greens on plates and garnish with cheese shavings. Melt butter with 3 TBS oil, stirring over low heat.
Arrange bread slices on baking sheet and brush both sides of bread with butter mixture.
Heat remaining 3 TBS oil in large skillet. Add onions and cook over low heat until soft. Add garlic and cook an additional minute. Add tomatoes and pepper flakes. Stir in one half of chopped basil at end of cooking time.