Preheat oven to 400 degrees F.
Spray 9x13" baking dish with cooking spray.
Unroll the crescent rolls and spread them out in the bottom of the pan, pressing the seams together to make one large sheet of dough. Set aside.
In a large skillet, heat olive oil over medium heat.
Add onion and cook until starting to soften, about 4-5 minutes.
Add zucchini and corn and cook another 4-5 minutes.
Add tomato, stir to combine, and remove from heat. If there is any extra liquid, try to discard it by dabbing with a paper towel.
Pour veggies over crescent roll.
Top veggies with cheese.
In medium bowl, whisk together eggs, milk, salt, and basil.
Pour over veggies and cheese.
Bake in preheated oven for 30-35 minutes, checking the last 10 minutes to make sure crescent rolls crust isn't getting too brown. If it is, cover with aluminum foil for the last 5-10 minutes.
Let sit for 10 minutes, then cut into squares and enjoy!