Heat the oven to 190 C / 375 F. Grease a 23 x 33 cm / 9 x 13-inch baking dish with a little of the olive oil.

Heat the remaining olive oil in a 10-inch skillet over medium heat. Add the garlic and cook 30 seconds until fragrant, then add the spinach in batches and cook 3 to 4 minutes until fully wilted.

Transfer the wilted spinach to a colander to cool slightly. Once cool enough to handle, squeeze it in a clean kitchen towel until no more liquid drips out. Chop roughly.

In a large mixing bowl, whisk the ricotta and eggs together until smooth and no streaks remain.

Stir in half the mozzarella, half the parmesan, salt, pepper, nutmeg, and oregano until evenly combined.

Fold the chopped spinach into the ricotta mixture until it's evenly distributed throughout.

Pour the mixture into the prepared baking dish and spread it into an even layer with a spatula.

Scatter the remaining mozzarella and parmesan over the top.

Bake for 30 to 35 minutes, until the top is golden and the center reaches 165 F / 74 C on an instant-read thermometer with no jiggle.

Rest for 10 minutes before slicing into squares and serving.