Ingredients :

• The shrimp — Get them raw—frozen and peeled is perfect and much easier than fresh. Pre-cooked shrimp will overcook in the oven and become rubbery. Medium to large size gives more bite.
• The Gruyère — This is what makes the crust. It melts differently than Emmental—fatsier, more intense, it creates that lacquered surface that browns well. Buy it in a block and grate it yourself; pre-grated bags are too dry and don’t melt the same way.
• Heavy cream — No light cream here. Heavy cream holds up to heat without separating and gives that coating consistency we’re looking for. Minimum 30% fat, liquid—not thick.
• Fresh spinach — Two large handfuls seem like a lot before cooking. After two minutes in a hot pan, there will barely be a cup left. Frozen works too—thaw them well and squeeze them dry by hand before use.