Mary Berry Potato And Onion Gratin Recipe

This comforting Mary Berry Potato And Onion Gratin Recipe layers wafer-thin slices of potato with sweet, butter-softened onions and a rich, nutmeg-scented cream sauce. Baked until bubbling and crowned with a golden crust of mature cheddar, it is the ultimate indulgent side dish that pairs effortlessly with Sunday roasts or grilled meats.

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Mary Berry Potato And Onion Gratin Ingredients

The Layers:

• 1 kg (2 lb 4 oz) Potatoes: Mary recommends a floury potato like Maris Piper or King Edward. They absorb the cream better and thicken the sauce naturally, unlike waxy varieties. Peeling is optional but recommended for a smoother texture.
• 2 large Onions: Thinly sliced.
• 40g (1 ½ oz) Butter: For sautéing the onions to bring out their sweetness before baking.

The Sauce & Topping:

• 300ml (½ pint) Double Cream: For luxurious richness.
• 150ml (5 fl oz) Milk: Lightens the mixture slightly so it isn’t too heavy.
• 1 Garlic Clove: Cut in half. Used to rub the dish for a subtle background aroma.
• 100g (4 oz) Mature Cheddar Cheese: Grated. Provides the savory, browned crust.
• Nutmeg: Freshly grated, to season the cream.
• Salt and Freshly Ground Black Pepper: To taste.

How To Make Mary Berry Potato And Onion Gratin

1. Prep the Oven and Dish: Preheat the oven to 200°C (180°C Fan / Gas 6). Take the cut garlic clove and rub the cut side vigorously all around the inside of a shallow, ovenproof gratin dish. This imparts a delicate garlic flavor without the risk of burning minced garlic pieces. Generously butter the dish afterwards.
2. Soften the Onions: Melt the butter in a frying pan over medium heat. Add the sliced onions and cook gently for about 10 minutes. You want them soft and translucent, but not browned or crispy. This pre-cooking ensures the onions melt into the final dish rather than remaining crunchy.
3. Prepare the Potatoes: Peel the potatoes and slice them very thinly. A mandoline is the best tool for uniformity, but a sharp knife works too. Crucial: Do not wash the potatoes after slicing; the starch on the surface helps thicken the cream sauce.
4. Layering: Arrange a layer of potato slices in the base of the dish. Scatter over half of the softened onions. Season with salt and pepper. Repeat with another layer of potatoes, the remaining onions, and seasoning. Finish with a final neat layer of overlapping potatoes on top.
5. The Cream Mixture: In a jug, mix the double cream and milk together. Season with a generous grating of fresh nutmeg, salt, and pepper. Pour this mixture slowly over the potatoes. It should seep down through the layers.
6. Bake: Sprinkle the grated cheddar cheese evenly over the top. Bake in the preheated oven for about 45–60 minutes. The potatoes should be tender when pierced with a knife, and the top should be deep golden brown and bubbling.
7. Rest and Serve: Allow the gratin to stand for 5–10 minutes before serving. This rest period allows the cream to settle and thicken, making it easier to spoon out.

Recipe Tips

• Potato Slicing: Uniformity is key. If some slices are thick and others thin, you will have a mix of mushy and raw bites. Aim for 3mm thickness.
• The Starch Factor: Keeping the starch on the potatoes (by not washing them after slicing) essentially creates a glue that binds the cream and milk into a sauce. If you wash them, the sauce may be watery.
• Browning Too Fast: If the cheese topping is getting too dark before the potatoes are tender, cover the dish loosely with foil for the remaining cooking time.
• Garlic Intensity: If you prefer a stronger garlic hit, you can crush the garlic and add it to the simmering cream/milk mixture instead of just rubbing the dish.

What To Serve With Potato And Onion Gratin

• Roast Lamb: The sweetness of the onions makes this the perfect partner for lamb.
• Steak: A luxurious alternative to fries or baked potatoes.
• Green Beans: Steamed greens cut through the richness of the cream.
• Gammon: The salty pork contrasts beautifully with the creamy potatoes.

How To Store Potato And Onion Gratin

• Refrigerate: Cover the cooled dish with foil or cling film and store in the fridge for up to 3 days.
• Reheat: This dish reheats wonderfully. Cover with foil to prevent the cheese from burning and bake at 180°C for 20–25 minutes until piping hot.
• Freeze: You can freeze the cooked gratin. Allow to cool completely, wrap well, and freeze for up to 2 months. Defrost in the fridge overnight before reheating.

Mary Berry Potato And Onion Gratin Nutrition Facts

• Calories: 350 kcal
• Fat: 22g
• Carbohydrates: 30g
• Protein: 8g
• Calcium: 200mg

Nutrition information is estimated per serving.

FAQs

Try More Recipes:

• Mary Berry Potato Rosti Recipe
• Mary Berry Potato Salad Recipe
• Mary Berry Sweet Potato Soup​ Recipe