Preheat oven to 350°F (180°C). Spray a deep-dish 9-inch pie plate with cooking spray; set aside.
In a large bowl, whisk together the Bisquick, oil, eggs, and salt. Add the Parmesan and cheddar cheeses; stir to combine.
Fold in the zucchini and onion.
Pour into prepared dish.
Bake for 40-45 minutes, or until cooked through and golden brown.
Video
Notes
A number of readers have said that this recipe works with less oil. I like to use the full ½ cup of oil to keep the pie nice and moist, but you can feel free to experiment with less fat. Let me know if you give it a try!
Any good melting cheese will work in this dish. For instance, swap out the cheddar and use Monterey Jack, Colby, Swiss, Gruyere, or Colby-Jack cheese.
Want a stronger cheese flavor? Use sharp cheddar (or another strong cheese) and feel free to increase the amount to 1 full cup.
Gluten-Free Version: Use Gluten-Free Bisquick (or another gluten-free baking mix) and make sure that your cheese and other ingredients are also certified gluten-free.
You do not need to squeeze the zucchini dry before using it in this recipe.
Use adeep-dish pie plate for a really thick zucchini pie!
Use a neutral oil that will not add flavor to the pie. I recommend either vegetable oil, canola oil, or avocado oil.
You can use thepre-grated Parmesan cheese that comes in a can, or you can shred your own cheese from a wedge of Parmesan. Either will work!
Serve the pie warm or at room temperature. I've even been known to enjoy the leftovers cold, straight from the fridge!
Garnish the pie with fresh herbs, such as basil, parsley, thyme, oregano, or chives.