Keto Tuna Casserole

Where tuna casserole comes from

Tuna casserole is about as American as a weeknight dinner gets. Casseroles took off in American homes in the 1950s, mostly because the ingredients were cheap and easy to find at the supermarket. Campbell’s put out a cookbook built around its canned soups in 1952, and it had a tuna casserole in it. That’s the version a lot of people know: canned tuna, egg noodles, a can of cream of mushroom soup stirred in, sometimes a handful of peas.

The topping was always the fun part. Breadcrumbs, crushed potato chips, fried onions or corn flakes went on top so the spoon cracked through something crunchy before it hit the creamy middle. It was also the dish people carried to potlucks, especially in the Midwest, and the one people brought over when somebody was sick or grieving, so they didn’t have to cook. A casserole that travels well and feeds a crowd has been doing that job for a long time.

At our table

I cook every recipe on this site in my own kitchen first. My bar for a low carb casserole is simple: it has to eat like the real thing, the way my cheesesteak casserole does. A tuna casserole has to clear that same bar, and the cheesy top helps a lot.

This is the kind of dinner that fits the busy stretch of the year. December fills up fast with school concerts, shopping and cookie baking, and the oven is spoken for half the week. A casserole that comes together from the pantry and a head of cauliflower saves a night. Then January comes, the holiday food is gone, and a big pan of something warm and cheesy that reheats for lunch is exactly what I want. If you’re already planning the holiday morning, my Christmas breakfast casserole is another one you can put together ahead and slide into the oven.

How a low carb tuna casserole works

Two things carry the carbs in the classic version: the egg noodles and the canned cream soup, which is thickened with wheat flour. Both are gone here.

Cauliflower takes the place of the noodles. Cut into small florets and steamed until a knife just slides in, it holds its shape in the oven and soaks up the sauce the way pasta does. The one thing to watch is water. Cauliflower keeps a lot of it, and so does canned tuna. Drain both well, and let the florets steam dry in the colander for a few minutes before they go into the sauce. That’s the difference between a creamy casserole and a soupy one.

The sauce stands in for the can of soup, and it’s barely more work. Butter, a little onion, celery and a full 8 ounces of sliced mushrooms go into a skillet until the mushrooms brown and their liquid cooks off. Then chicken broth, cream cheese and heavy cream get whisked in and simmered for a few minutes. The cream cheese is what makes it thick without flour. A cup of sharp cheddar and a teaspoon of yellow mustard finish it off.

Four cans of tuna is more than most old recipes use, and it’s on purpose. It’s where most of the protein comes from. For the crunchy top, grated parmesan and a couple of spoonfuls of almond flour go over the last of the cheddar, and they bake into a golden crust you can hear when the spoon goes in.

The numbers come from USDA FoodData Central. Each serving has 446 calories, 30 grams of protein, 12 grams of total carbs, 3 grams of fiber and 32 grams of fat, so net carbs come to about 9 grams. Peas aren’t in this one, since they add carbs fast. If you stir some in, they aren’t counted in those numbers.

The tuna is already cooked in the can, so the oven is just heating everything through and browning the top. Still, use a thermometer and bake until the center reaches 165°F (74°C), the safe temperature for casseroles and leftovers. That usually takes 20 to 25 minutes at 400°F.

A few swaps that keep it low carb:

• Use canned salmon or albacore tuna in place of the chunk light tuna.
• Swap the cheddar for Monterey Jack, Swiss or Gouda.
• Use chopped broccoli florets for half of the cauliflower.
• Skip the almond flour and top with parmesan alone.