Step 1

Preheat your oven to 375 degrees F. Grease a 9x13 glass pan with butter.

Step 2

Rinse your zucchini and slice off the tip and root ends. Pat your zucchini dry with a paper towel. Leave the skin on.

Step 3

Slice your zucchini into 1/8-inch rounds, using a mandoline, food processor or paring knife. Place your zucchini slices into a large mixing bowl.

Step 4

Using paper towels, pat your zucchini slices and gently squeeze them to absorb excess moisture. (This is key to prevent a soggy casserole.)

Step 5

Peel and finely chop your onion and add it to your bowl.

Step 6

Add your pressed garlic (or peel and chop it finely).

Step 7

In a liquid measuring cup, add your oil, then beat in your eggs with a fork. Pour the egg/oil mixture into your bowl with the zucchini.

Step 8

Add your flour, baking powder, Parmesan, Romano, salt, pepper and basil to your bowl.

Step 9

Use a wooden spoon to carefully mix everything until combined well. Try to separate any zucchini slices that are stuck together.

Step 10

Transfer your zucchini mixture to your greased pan and smooth it out evenly. Bake uncovered for 55-60 minutes, or until the entire top is browned (but not burned).

Step 11

Let the casserole rest for at least five minutes before slicing it. Garnish with parsley, if desired.

Step 12

Store leftovers in the refrigerator for up to five days.