Using fresh spinach gives the best texture and flavor, as it wilts down beautifully into the sauce.

Unsalted butter is ideal for controlling the saltiness of the dish.

Shallots offer a milder, sweeter onion flavor compared to regular onions, which is perfect for this creamy dish.

Freshly minced garlic adds a wonderful aromatic depth.

All-purpose flour acts as our thickening agent, helping to create a smooth, velvety sauce.

Kosher salt has a cleaner taste and is easier to control than table salt. Adjust to your preference.

Freshly ground black pepper adds a gentle warmth. White pepper can be used for a slightly different subtle spice.

A tiny pinch of nutmeg enhances the creamy, cheesy flavors without being overpowering.

Provides a good base for our sauce.

Adds richness and a luxurious mouthfeel to the cream sauce.

Offers a sharp, salty tang that complements the spinach.

Brings a nutty, slightly sweet complexity that melts beautifully.

If you don’t have Romano, good quality grated Parmesan cheese is an excellent substitute. For Gruyere, Swiss or Emmental cheeses will also work beautifully, offering a similar nutty flavor.

For a subtle hint of heat, add a pinch of red pepper flakes along with the salt and pepper.

If you’re a big garlic fan, feel free to add an extra clove or two when sautéing the shallots.

Squeezing out all the excess water from the spinach is a crucial step to prevent a watery gratin. Make sure it’s as dry as possible before adding it to the sauce.

Boiling the spinach for just one minute is enough to wilt it for easy chopping and processing.

When simmering the sauce, a gentle simmer is key to allow it to thicken without scorching. Stirring occasionally helps ensure even cooking.

If you choose to broil, keep a very close eye on your gratin, as it can go from perfectly golden to burnt in a matter of seconds.

Taste your sauce before transferring it to the baking dish. Adjusting salt and pepper at this stage ensures a perfectly seasoned final dish.

While fresh spinach is recommended for the best texture, you can use frozen spinach. Make sure to thaw it completely and squeeze out as much water as possible before chopping and adding it to the sauce. You might need a bit more to get the same volume.

A standard pie dish or a small 8×8 inch baking dish works wonderfully. You want something that will allow the gratin to heat through evenly and get that lovely bubbly top.

Yes, you can prepare the spinach and sauce mixture ahead of time, store it in the refrigerator, and then top with cheese and bake just before serving.

The chopped spinach can be blanched, squeezed, and chopped a day in advance and stored in an airtight container in the refrigerator. The sauce can also be made up to the point of adding the spinach and cheeses, then refrigerated.

When ready to serve, reheat the sauce gently if needed, stir in the spinach and cheeses, transfer to your baking dish, top with the remaining cheeses, and bake as directed. It might take a few extra minutes to heat through if starting from cold.

Leftovers can be stored in an airtight container in the refrigerator for 2–3 days. Reheat gently in the oven or microwave.