Keto Celeriac Gratin with Cream and Cheese
Potato gratin, thin slices baked in cream under a crisp cheese crust, is Sunday-dinner or Christmas food for many people. The classic recipe carries around 35 g of carbs per serving, well outside the keto budget. Celeriac gives you almost the same look and a surprisingly similar mouthfeel: each serving lands at 5 g net carbs, 38 g fat and 13 g protein.
Key points at a glance
- Total time: approx. 1 hour, including 45 minutes in the oven.
- Approx. 5 g net carbs and 38 g fat per serving.
- Main ingredients: celeriac, cream, Gruyère, garlic, thyme.
- Key tip: slice the celeriac really thin, ideally with a mandoline.
Ingredients
Serves 4 as a side or 2 as a main course.
| Amount | Ingredient | Note | ||
|---|---|---|---|---|
| Celeriac | peeled weight, thinly sliced | |||
| peeled weight, thinly sliced | ||||
| Cream | - | |||
| Gruyère | grated | |||
| grated | ||||
| Garlic cloves | - | |||
| Butter | approx. 1 tbsp, for greasing | |||
| approx. 1 tbsp, for greasing | ||||
| Thyme leaves | 1 tsp, fresh | |||
| 1 tsp, fresh | ||||
| Salt | to taste | |||
| to taste | ||||
| Nutmeg | to taste | |||
| to taste | ||||
| White pepper | to taste | |||
| to taste | ||||
How to make it
Preheat the oven to 180 degrees Celsius (top/bottom heat). Peel the celeriac and use a mandoline or a sharp knife to cut it into 2 to 3 mm slices. The thinner the slices, the better the cream soaks in. Rub a baking dish (approx. 20 x 25 cm) with a cut garlic clove, then grease it with butter. Layer the celeriac slices fanned out or stacked. In a small saucepan, bring the cream to a brief boil with 1 crushed garlic clove, 1 tsp salt, a pinch of nutmeg and a little white pepper. Pour over the celeriac. The dish should be about two-thirds full of liquid. Scatter with thyme leaves and cover with aluminium foil. Bake for 30 minutes, then remove the foil and sprinkle 120 g of grated Gruyère on top. Bake uncovered for another 15 minutes until the top is golden brown and bubbling. Let the gratin rest for 5 minutes before serving.
Why does celeriac work so well in a gratin?
Celeriac behaves a lot like potato when it cooks: it absorbs liquid, softens through, and still keeps its shape. Its nutty flavour pairs beautifully with cream, garlic and hard cheese, arguably better than the floury neutrality of a potato. Per 100 g it delivers just 2.4 g of net carbs, roughly one-seventh of what you get from potato.
Source: USDA FoodData Central, Celeriac, raw , USDA FoodData Central, Cream, heavy whipping
Which cheese works best?
Gruyère is the classic choice: it melts evenly, doesn't pull into stringy threads, and brings a gentle nutty note. Good alternatives are Comté, aged Alpine cheese or Emmental. For a sharper flavour, mix 30 g of Parmesan into the Gruyère. Less suitable: young Gouda, which melts too greasy. Mozzarella melts well but is too mild for a gratin and doesn't deliver a properly golden crust. If you like a creamier sauce, stir 1 tbsp of cream cheese into the cream before pouring it over.
Tips for a successful celeriac gratin
- Slice the celeriac really thin, ideally with a mandoline.
- Cover with foil for the first 30 minutes, otherwise the cream dries out.
- Add the cheese only in the last 15 minutes, otherwise it burns.
- Let it rest for 5 minutes before serving so the sauce can set.
- Gruyère melts better than young Gouda and brings more flavour.
Nutrition values
| Nutrient | Per serving | Keto context |
|---|---|---|
| Calories | approx. 450 kcal | Filling side or main course. |
| Filling side or main course. | ||
| Fat | approx. 38 g | From cream and cheese. |
| From cream and cheese. | ||
| Net carbs | approx. 5 g | Low. |
| Low. | ||
| Protein | approx. 13 g | From Gruyère. |
| From Gruyère. | ||
| Fibre | approx. 3 g | Moderate. |
| Moderate. | ||
| Salt | approx. 1.8 g | Cheese brings its own salt. |
| Cheese brings its own salt. | ||
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
Won't the celeriac stay tough in the gratin?
If you slice it thin enough, ideally 2 to 3 mm, the hot cream softens it through and turns it creamy. For thicker slices, blanch them in boiling water for 5 minutes first.
Can I prepare the gratin in advance?
Yes, it works very well. The fully baked gratin keeps in the fridge for 2 days and reheats in the oven at 160 degrees Celsius for 20 minutes. Assembled but unbaked, the layered gratin holds for about 12 hours in the fridge. Pour over the cream and bake just before serving.
What dish size should I use?
A shallow baking dish around 20 x 25 cm works well. The key point is that the celeriac layers shouldn't be more than 4 cm deep, otherwise the centre won't cook through before the top burns.