Preheat oven to 425℉.

In a large pot, add a few inches of water and a good pinch of salt and bring to a boil.

Add the spinach and use tongs to push it and toss it in the water for one minute.

Drain spinach and run under cold water to cool quickly. Squeeze out as much liquid as possible and roughly chop the spinach. Set aside.

In a large skillet, melt the butter over medium heat. Add the shallots and cook until soft and translucent, about 3 - 4 minutes.

Whisk in garlic and stir until fragrant. Whisk in flour, salt, pepper, and nutmeg.

Whisk for a minute or two, then slowly pour in the milk and cream. Bring to a gentle boil and cook uncovered, stirring occasionally, until the cream is thick enough to coat the back of a wooden spoon, about 10 minutes.

Remove from heat and combine the spinach and the sauce in the skillet.

Mix in half of the Romano and half of the Gruyere. Adjust for salt.

Transfer into a 9-inch pie dish or small baking dish.

Top with remaining Romano and Gruyere cheese.

Bake for 15 minutes or until bubbling. If the top isn’t golden brown, place it under the broiler for a minute or two.