Heat oven to 350°F. Lightly spray 11-inch pie plate with cooking spray.
Unroll dough; separate into 8 triangles. Line pie plate with dough triangles, making sure shortest sides of triangles are at edge of pie plate. Refrigerate.
In 10-inch skillet over medium heat, cook onion and tomatoes about 5 minutes, stirring occasionally, until they begin to soften. Remove from heat; set aside.
In medium bowl, beat eggs, milk and cream with whisk until well combined. Add tomato mixture and 3 cups of the cheese; fold in with wooden spoon.
Remove pie crust from refrigerator. Pour tomato-egg mixture into crust, spreading to remove any large lumps. Sprinkle remaining 1/4 cup cheese over top.
Bake about 1 hour or until center is firm to the touch. After 20 minutes of baking, place ring of foil around edge of pie to prevent crust from burning. Cool for at least 1 hour before serving.