
Growing up, tuna pasta bake was my favourite favourite thing to eat. This comforting bake using tuna, spinach and onions is just as warming and delicious, without the pesky carbs. It also happens to be much quicker and easier to make. Win!
I love using frozen spinach because it’s so convenient, but you’re welcome to use any fresh greens. Just wilt them with a little olive oil before using.

Cheesey Tuna & Spinach Bake
Ingredients
- 2 onions sliced
- 1 packet frozen Spinach 250g / 9oz, defrosted
- 2 medium cans tuna 200g / 7oz each, drained
- 1/2 cup sour cream
- 2 handfuls grated cheese
Instructions
- Heat a little oil in a medium oven-proof frying pan on a medium high heat. Add onion and cook, stirring often until onion is soft and golden.
- Preheat your oven to 250C (480F). When the onion is cooked, remove from the heat. Stir in spinach, tuna and sour cream. Smooth the top and sprinkle over cheese.
- Bake for 10 minutes or until cheese is melted and everything is hot.
WINE MATCH: A crisp dry white like a Gruner Veltliner or Riesling.
Variations & Substitutions
pantry-friendly – sour cream = pesto.
no oven-proof frying pan – cook the onion and transfer to an oven proof pot, dish or springform pan. You want it to be about 24 cm (9in) diameter but don’t stress too much.
fresher – serve with a squeeze of lemon.
different greens – use any frozen or pre-cooked greens. Kale is great as are collard greens or chard (silver beet).
different cheese – I use a melting cheese like emmental or gruyere but any melting cheese like cheddar or swiss is good.
more substantial (carb-lovers) – toss in cooked pasta before baking or serve with crusty bread and butter.
more substantial (low carb) – extra tuna or spinach. Add some roast almonds.
vegetarian – replace tuna with cooked chickpeas, lentils or boiled eggs. Also thinking mushrooms would be lovely cooked in with the onions. Add some sunflower seeds.
carnivore – replace tuna with bacon, ham or ground meat (brown in pan first).
dairy-free – try replacing the sour cream with the dairy-free variation of my pesto and using sliced almonds instead of the melted cheese. Actually that sounds delicious – mental note to try the pesto version.
keto / ultra low carb – cheese = parmesan.
Waste Avoidance Strategy
onion – will keep in the pantry for months. Best if in a dark corner in a brown paper bag.
frozen Spinach – will keep in the freezer for months.
cans tuna – keep them in the pantry.
sour cream – keeps for weeks in the fridge.
cheese – most hard and melting cheeses will keep for weeks wrapped in waxed paper or baking paper and stored in an airtight container (or sealed ziplock bag) in the fridge. If you need to store for longer cheese can be frozen.
Prepare Ahead
Absolutely. Assemble ahead but don’t melt the cheese. Keep in the fridge for up to 2 weeks or freeze. To serve pop in the hot oven until cheese is melted.


Add to my Old Favourite Recipes
I made this for lunch today, and while it tasted pretty good, I’m not sure I can do it again, mostly because of the way my house now smells. I used a single 5-oz. can of tuna, Greek yogurt in place of sour cream, added a handful of almonds, and topped with Chihuahua cheese, a nice melty cheese. This made plenty to meet our older appetites and our nutritional needs. I wish I could tolerate post-cooking smells better, because this is definitely a nice way to do tuna.
Maybe you need an outdoor kitchen Susan 🙂
Actually Susan, I was just thinking you could roast the onion instead – just make sure you stir often enough so it cooks evenly – cheaper than an outdoor kitchen 🙂
Made this again today, and had no problem with cooking smells. I divided the tuna mix between two 2-cup bowls for baking, and that worked very well – much easier than trying to deal with a cast iron frying pan…
Yay Susan!
Cooked this tonight and squeezed some lemon over the top. Delicious. May add some garlic and chili next time. Thanks Jules.
Excellent Anna!
Garlic and chilli is always a good idea 🙂
Delicious and so easy to make. I will definitely be making it again.
Excellent Karen!
Not counting this as part of the challenge, but I liked this one so much I made it again! 🙂
You can count it if you like Lina!
On a hot day, I didn’t want to use the oven. This was just as good prepared in one pan on the stove top. And if you make extra, leftovers are good cold.
Good to know Debbie!
Made this one as part of the 10 day challenge. New to meal plans and had shopped before I had the challenge weeks recipes.
Loved it. Simple and tasty, is in my favourites list.
Excellent Lina! – I need to make this again soon. Thanks for the reminder 🙂
Made this with wilted spinach. I feel it could use some spice, but I don’t know what. Maybe I’ll try a dash of lemon juice.
Lemon is always a great idea if you can’t put your finger on what’s missing Paul!
On the spice front – I’d go with smoked paprika or some chilli as a first port of call.
Thanks, Jules , it’s another winner! I tried the pesto instead of cream, but did add the cheese on top. Also mixed in some turmeric. Super yummy! So good I was eating spoonfuls of the mixture before I put it into bake…just to try out 😉
p.s. I tried it with pink salmon instead of tuna – worked fine! Love how versatile these recipes are.
ooh Yum Amrita – LOVING the sound of your pesto and salmon version!