Preheat oven to 425°F. Line a baking sheet with Gefen Parchment Paper and spray well with nonstick cooking spray.

Place onions on baking sheet. Toss with olive oil and sprinkle with salt. Bake for 1 hour (onions will caramelize).

Lower oven temperature to 400°F. Add zucchini and red pepper to baking sheet. Bake an additional 30 minutes.

Combine all ingredients for the crust. Knead until dough is smooth. It should be easy to work with. Press evenly into a 10-inch tart pan (or 10-inch disposable pan).

In a bowl, combine the eggs, milk, flour, salt, and pepper. Use an immersion blender to blend until smooth.

Lower oven temperature to 375°F.

Place onions and vegetables inside crust. Top with basil and shredded cheese. Pour batter over vegetables and cheese.

Bake for 45 minutes, until crust is golden and center is set.