This unphotogenic yet rewarding marvel is largely based on a recipe I hounded out of a now-deceased cousin, and is known in my family as "the tilapia thing."
"I don't have much time tonight, I'll make the tilapia thing."
"Ugh, those peppers are on their way out, I'm going to slice them and put them on top of the tilapia thing."
"We need to finish these brownies stat, I want that dish to make the tilapia thing in."
You get the idea. It's special! It doesn't sound that great, but it's cheap and easy and delicious and super-nutritious. I usually don't serve anything with it except white wine, because I just like to dump a bunch of it in a bowl and then eat it while watching television. But you could probably use some little roasted potatoes. No vegetables or salad, though, or you'll be up to your gills in roughage. It's one of those things where you're eating it and you say "and it's so good for you!" with your mouth full. And I'm giving you my version of the recipe, which involves more fat than the original, which enhances both the deliciousness and the nutrition. Tell me quadrupling the feta was an expensive mistake. Go on.
Preheat your oven to 425 degrees, and oil or cooking spray a glass dish (I use one of these guys here.) There's no way to make that step sound conversational.
Now, you want a lot of baby spinach. The recipe calls for, like, a ten ounce bag, but I don't really think that's enough spinach. I usually use one of the big tubs, because you're going to wilt it, and baby spinach cooks down to a tiny fraction of its original bulk. It's like it actually changes states, or something. I just keep tossing it in and wilting it until I run out of space in the skillet, and then I have an handful of leftover spinach that eventually liquifies in my crisper drawer and needs to be sponged out with a paper towel. But I'm getting ahead of myself.
You may not have wilted greens before, it's great, and it smells amazing! Heat some olive oil in a skillet over medium low heat. I just use my nonstick for this, use the biggest one you have. Sometimes I even use a wok, so I'm not dropping half-wilted spinach off the sides of my skillet onto the burners. Again, the recipe calls for one tablespoon of olive oil, but I start with two or three and then add more as I go. Stir in some garlic. I buy minced garlic, and then I drop in a big spoonful, but it's probably a couple of cloves, if you want to chop your own. I read a scary book about someone giving their entire dinner party botulism with jarred garlic, so now I use the smaller squeezy bottles of minced instead of the big glass jars. Your call! Okay, cook the garlic in the oil until it gets brown and smells great. Now, just dump in one handful of spinach at a time, it'll become dark green and wet and small. Keep adding until you run out of space. Congratulations, you are done with the hard part, and it was totally easy.
Next, you want a cup of salsa (of your choosing!) Ideally, you'll want to take a second and dump the cup of salsa through a strainer to make it less watery, but sometimes I skip that part. Stir the salsa into the spinach, take it off the heat.
Spread half of your salsa-y spinach onto the bottom of your baking dish (it may not cover the whole thing). On top, you're going to place your fish fillets in a single layer. Right! The fish. Just some cheap-ass white fish. It doesn't really matter. Basa, haddock...I use tilapia. About a pound and a half of it, but you can squish in more or less based on how many people you're feeding. Put the other half of the salsa-y spinach on top. This is a good time to add random vegetables you're trying to use up (sliced peppers, mushrooms, or zucchini work best) if you want. Now douse the whole thing in chunks of feta cheese with a few turns of black pepper. Tons of feta. It'll brown in the oven and be gorgeous. Hand-to-God, the original recipe is like 1/4 cup of feta. Silliness!
Now, put it in the oven for half an hour, check to make sure the fish is flaky and cooked through, serve with the pan juices on top. Eat it.