Step 1

Preheat your oven to 350° F. Spray a 9 x 9 baking dish with cooking spray.

Step 2

Heat the oil in a large skillet to medium-high heat. Add the onion and cook for 6 minutes; add garlic and cook for 1 more minute.

Step 3

Stir in the spinach and the cream cheese. Turn the heat to low. Cook until the cream cheese is fully incorporated.

Step 4

Remove from heat and stir in the sour cream, heavy cream, Gruyere, salt, and pepper. When the mixture is thoroughly combined, add the egg.

Step 5

Transfer to the prepared baking dish and top with the parmesan cheese.

Step 6

Cook for 35 minutes, until golden brown.