1 cup + 1 tablespoon (149 g) all purpose gluten free flour (I used Better Batter)
1/2 teaspoon xanthan gum (omit if your blend already contains it)
2 tablespoons (18 g) cornstarch
1 teaspoon baking powder
1/8 teaspoon baking soda
1 1/4 teaspoons kosher salt
1 tablespoon dried parsley
1/2 teaspoon dried oregano
1 1/2 teaspoons garlic powder
3/4 cup (75 g) finely grated Parmigiano Reggiano cheese, plus more (shredded or grated) for sprinkling
Heaping 3 1/3 cups (375 g) grated raw zucchini
5 eggs (250 g, weighed out of shell), at room temperature
1/2 cup + 2 tablespoons (140 g) extra virgin olive oil
2 tablespoons (30 g) sour cream, at room temperature
1 small yellow onion, peeled and grated
Fresh flat leaf parsley, chopped (optional, for serving)
Preheat your oven to 350°F. Grease the bottom and sides of a 13-inch x 9-inch x 2-inch baking pan. Set it aside.
In a large bowl, place the flour, xanthan gum, cornstarch, baking powder, baking soda, salt, parsley, oregano, garlic powder, and 3/4 cup cheese, and whisk to combine. Add the grated zucchini, and mix to combine and evenly distribute the zucchini throughout the dry ingredients. In a separate small bowl or 1 quart or larger measuring cup, place the eggs, oil, sour cream, and grated onion, and whisk to combine well.
Create a well in the center of the dry ingredients in the large bowl, pour in the egg and oil mixture, and mix to combine. The mixture will be thick but soft. Transfer it to the prepared pan and spread into an even layer. Sprinkle the top evenly with the remaining grated or shredded cheese.
Place the pan in the center of the preheated oven and bake until puffed and lightly golden brown (about 30 minutes). Allow the casserole to cool for at least 10 minutes in the baking pan before cutting it into 2-inch squares. Sprinkle with the optional chopped fresh parsley, and serve warm or at room temperature. Store any leftovers in a sealed container in the refrigerator.
Adapted from Betty Crocker (hat tip to the mom on my daughter’s softball team for the idea!)