Prepare and pre-bake the pastry according to package directions in an 11-inch tart pan with a removable bottom. Allow to cool slightly before filling.
Preheat oven to 375 degrees
Wash and slice the tomatoes and place on a paper towel lined plate to drain.
Cook onions in a skillet with a touch of olive oil until soft.
In a medium mixing bowl combine the eggs, milk, flour and chopped basil. Whisk until well blended.
Sprinkle the shredded cheese in the bottom of the baked crust. Layer half the tomatoes over the cheese. Pour the egg mixture over the tomatoes and cheese. Top with the remaining tomatoes and onions.
Bake for 30 minutes or until the egg mixture is set in the center. Tent the quiche with Reynolds Wrap® Aluminum Foil during baking if the crust browns too quickly.
Remove from the oven and allow the quiche to cool for 10-15 minutes before serving.