Keto Tuna Eggplant Casserole with Parmesan
This keto tuna eggplant casserole layers eggplant slices with a tuna and cream cheese filling and tomato passata, dusts everything with Parmesan, and bakes it golden brown. The result: 55 g protein at 7 g net carbs — a filling keto casserole that also works very well for meal prep.
Key Facts at a Glance
- Preparation time: approx. 35 minutes — 10 minutes prep, 25 minutes in the oven.
- Approx. 7 g net carbs and 38 g fat per serving.
- Ingredients: tuna (2 cans), eggplant, cream cheese, tomato passata, Parmesan, garlic, olive oil, oregano.
- Suitable as a keto dinner for meal prep — keeps for 3 days, served cold or warm.
Ingredients
One serving equals half of the casserole (recipe yields 2 servings) — intended as a complete keto dinner.
| Amount | Ingredient | Note | ||
|---|---|---|---|---|
| Tuna in water | 185 g each, drained approx. 270 g | |||
| 185 g each, drained approx. 270 g | ||||
| Eggplant | 1 large, in 5-mm slices | |||
| 1 large, in 5-mm slices | ||||
| Double-cream cream cheese | or full-fat cream cheese | |||
| or full-fat cream cheese | ||||
| Tomato passata | approx. 100 g | |||
| approx. 100 g | ||||
| Parmesan (grated) | - | |||
| Garlic cloves | - | |||
| Olive oil | approx. 1 tbsp | |||
| approx. 1 tbsp | ||||
| Oregano (dried) | 1 tsp | |||
| 1 tsp | ||||
| Salt | to taste | |||
| to taste | ||||
| Pepper | to taste | |||
| to taste | ||||
Preparation
-
Prepare the eggplant and preheat the oven
approx. 12 minutes2 cans Tuna in water 185 g each, drained approx. 270 g 300 g Eggplant 1 large, in 5-mm slices 0.5 tsp Salt to taste Preheat the oven to 200 °C (top/bottom heat). Cut the eggplant (300 g) crosswise into slices approx. 5 mm thick. Lightly salt the slices on both sides and let them sit on kitchen paper for 10 minutes — this draws out water. Then pat dry with fresh kitchen paper.
-
Mix the filling and layer
approx. 5 minutes150 g Double-cream cream cheese or full-fat cream cheese 100 ml Tomato passata approx. 100 g 40 g Parmesan (grated) 2 clove Garlic cloves 15 ml Olive oil approx. 1 tbsp 2 g Oregano (dried) 1 tsp 0.3 tsp Pepper to taste In a bowl, combine the tuna (from 2 cans, very well drained) with cream cheese (150 g), 2 finely chopped garlic cloves, oregano (1 tsp) and pepper. Brush a baking dish (approx. 20×20 cm) with olive oil (15 ml). Lay in the first layer of eggplant slices, spread half of the tuna mixture over them, add 50 g of tomato sauce on top. Add a second layer of eggplant, the remaining filling and remaining tomatoes on top. Sprinkle Parmesan (40 g) evenly over the top.
-
Bake and serve
approx. 25 minutesSlide the baking dish onto the middle rack of the preheated oven. Bake for 22–25 minutes until the Parmesan is golden brown. Take out of the oven and let rest for 5 minutes. Cut into two portions with a sharp knife and serve.
You did it! Enjoy every delicious bite.
Which tips help with the keto tuna eggplant casserole?
- Salt the eggplant slices and let them draw water for 10 minutes, then pat dry — this prevents a watery casserole.
- Drain the tuna very well and loosen it up with a fork before mixing with the cream cheese.
- Lightly oil the baking dish so the bottom eggplant layer doesn't stick.
- Only sprinkle the Parmesan on in the last 5 minutes and briefly slide under the broiler for an especially crispy crust.
- Cut the eggplant slices approx. 5–6 mm thin — thick slices will not cook through completely.
Why this casserole fits keto well
Tuna in water (2 cans of 185 g each, drained approx. 270 g of fish) delivers around 63 g of protein at practically 0 g carbs and only about 3 g fat — it is the most protein-rich of the common canned options. Eggplants have a low carb content at approx. 3 g net carbs per 100 g and a meaty texture that pairs well with the tuna filling. Cream cheese (150 g) brings around 4 g protein and 32 g fat, binds the filling and makes it creamy. Tomato passata (100 g) provides approx. 4 g net carbs. Parmesan (40 g) on top adds 15 g protein and glutamate — which boosts the umami flavor without carbs. In total this comes to approx. 55 g protein, 38 g fat and 7 g net carbs at approx. 590 kcal.
Source: USDA FoodData Central – Tuna, light, canned in water , FDDB Nutrition Database
Eggplant as a keto vegetable in casseroles
Eggplants (Solanum melongena) have approx. 3 g net carbs per 100 g and are one of the few vegetables that retain a similarly firm texture to pasta sheets when layered in casseroles — especially when the slices are salted and lightly pan-fried beforehand. Salting draws water out of the eggplant and prevents the casserole from becoming too watery.
Canned tuna: protein and omega-3
Tuna in water is the most affordable high-protein source for keto: approx. 23 g of protein per 100 g drained at under 1 g of fat. Tuna also contains omega-3 fatty acids (EPA and DHA), though less than fatty fish such as salmon. In the casserole, tuna does not lose any meaningful nutrients due to the heat.
Source: NIH ODS – Omega-3 Fatty Acids
How do I serve and vary the tuna casserole?
Let the casserole rest for 5 minutes straight out of the oven before portioning — the layers will hold together much better. A simple green salad makes a good side. From my own experience, I recommend briefly pan-frying the eggplant slices before layering — it gives the casserole more depth than raw layered eggplant.
Meal prep: equally good cold or warm
The casserole keeps for 3 days in the fridge and tastes just as good cold (as a snack or in a lunchbox) as warm. To reheat: 5 minutes at 160 °C in the oven or 2 minutes in the microwave. Freezing single portions is possible — up to 1 month.
Variant without tuna
Canned sardines (same protein content, more omega-3 fat) work equally well. Chicken breast (200 g diced, lightly pan-fried) is a meat alternative. For a vegetarian variant: 200 g ricotta instead of tuna — the protein content drops to approx. 30 g per serving.
Nutrition values
| Nutrient | Per 100 g | Per serving | Keto classification |
|---|---|---|---|
| Calories | approx. 155 kcal | approx. 590 kcal | Medium-light keto dinner; energy from protein (tuna, Parmesan) and fat (cream cheese, Parmesan). |
| Medium-light keto dinner; energy from protein (tuna, Parmesan) and fat (cream cheese, Parmesan). | |||
| Fat | approx. 10 g | approx. 38 g | Mainly saturated fatty acids from cream cheese; Parmesan adds medium fat content. |
| Mainly saturated fatty acids from cream cheese; Parmesan adds medium fat content. | |||
| Net carbs | approx. 1.8 g | approx. 7 g | Low; comes from eggplant and tomato sauce — under the daily keto limit. |
| Low; comes from eggplant and tomato sauce — under the daily keto limit. | |||
| Sugar | approx. 1.0 g | approx. 3.5 g | Natural sugar from tomatoes and eggplant; no added sugar. |
| Natural sugar from tomatoes and eggplant; no added sugar. | |||
| Protein | approx. 14.5 g | approx. 55 g | Very high; tuna is one of the most protein-rich ingredients overall, complemented by Parmesan and cream cheese. |
| Very high; tuna is one of the most protein-rich ingredients overall, complemented by Parmesan and cream cheese. | |||
| Salt | approx. 0.6 g | approx. 2.2 g | Moderate to high; Parmesan and tuna naturally bring salt — do not add extra salt before baking. |
| Moderate to high; Parmesan and tuna naturally bring salt — do not add extra salt before baking. | |||
Note: Nutrition values are estimated averages per 100 g and per serving and may vary depending on ingredients, brands, portion size, and preparation. They do not replace individual nutrition or medical advice.
FAQ
Is tuna in water or oil better for keto?
Both are suitable for keto. Tuna in water has less fat (approx. 1 g/100 g) and more protein — good if you want to control the fat source yourself (e.g. through olive oil or cream cheese). Tuna in olive oil has approx. 8 g of fat and more calories, is juicier and is better suited for salads without additional fat sources.
How do I prevent the casserole from becoming too watery?
Two steps: (1) Salt the eggplant slices, let them sit for 10 minutes and pat dry. (2) Drain the tuna very well and press it out firmly. These two measures significantly reduce the water content and ensure a compact casserole.
Can I prepare the casserole the day before?
Yes: assemble the casserole, cover with cling film and store in the fridge. The next day, place it straight into the oven preheated to 200 °C — baking time extends by approx. 5 minutes since the casserole goes in cold.
Does this dish work for losing weight on keto?
Very well: at 590 kcal and 55 g protein it is one of the lowest-calorie keto dinners with a very high protein content. The protein from tuna is very satiating. For further calorie reduction: reduce the cream cheese to 100 g — calories then drop to approx. 480 kcal.