This also works well with Tilapia and boneless, skinless Chicken Breasts although you do have to pound them out to flatten.
2 tablespoons unsalted butter
1 medium onion; chopped
1/2 teaspoon kosher salt
1 clove garlic; minced
1 10 oz. Frozen spinach ; thawed and squeezed dry
1 lemon, zested
1/4 teaspoon freshly ground black pepper
2 tablespoons chopped fresh parsley leaves
1 cup heavy cream
1/4 cup White wine
10 ounces Cheddar; grated
1 1/2 lbs to 2 pounds flounder fillets
3 cups leftover cooked rice
Preheat the oven to 350 degrees F. In a medium saute pan over low heat, melt the butter; add the onion and a pinch of salt and cook until translucent. Add the garlic and continue to cook for another minute; then add the spinach and lemon zest. Cook until just heated through. Season with the salt and pepper, add the parsley, and stir to combine. Remove from the heat and keep warm.
Place the heavy cream and wine into a saucepan over medium heat. Once the mixture begins to simmer, gradually add the cheese and stir until melted. Set aside and keep warm.
If the fillets are large, cut in half. Season each filet on both sides with salt and pepper. Divide the spinach mixture evenly among the fillets and roll the fish around the mixture. Place the rice into a 2 1/2-quart casserole dish and spread evenly. Place each roll on top of the rice, seam side down. Pour over the cheese sauce and place in the oven for 25 minutes. Allow to cool for 5 minutes before serving.