In a blender, add basil, broccoli, oil, pine nuts, milk and garlic. Blend until smooth. (It will be a little thick. You may add more milk for a thinner consistency.)
In a medium bowl, mix zucchini, peppers and onions with oil and Italian seasoning.
Place flatbreads on a baking sheet and spread 2-3 tablespoons broccoli pesto sauce on top. Top with marinated vegetables and cheese.