Scalloped Potatoes

Ingredients

• 42 g (3 tbsp)unsalted butter
• 57 g (2 oz)plain flour
• 488 ml (16.5 fl oz)whole milk
• 237 ml (8 fl oz)vegetable stock
• 4garlic cloves, grated
• 15 ml (1 tbsp)thyme, chopped
• 10 g (2 tsp)salt
• 1 g (½ tsp)black pepper
• 1,361 g (48 oz)Yukon Gold potatoes, sliced
• 1onion, sliced
• 340 g (12 oz)Cheddar, grated

Instructions

1. 1

   Preheat the oven

   Heat the oven to 200°C (400°F) and grease a baking dish.

2. 2

   Make the sauce

   Melt the butter in a saucepan over medium heat. Whisk in the flour and cook for 1 minute. Gradually pour in the milk, whisking to combine, then whisk in the vegetable stock.

3. 3

   Season the sauce

   When the sauce is smooth, add the grated garlic, chopped thyme, salt and black pepper. Keep whisking for 3 minutes, then take the pan off the heat.

4. 4

   Layer the ingredients

   Arrange half the sliced potatoes in the baking dish. Add half the onion, half the sauce and 113 g (4 oz) of the grated Cheddar. Repeat with the remaining potatoes, onion, sauce and cheese.

5. 5

   Bake until golden

   Cover the dish with foil and bake for 30 minutes. Remove the foil and bake for a further 40 minutes, until the cheese is melted and golden brown. Leave to stand for 10 minutes before serving.

What are scalloped potatoes?

Scalloped potatoes are thin slices of potato baked in a creamy sauce, often with cheese added. The dish is especially familiar in North American home cooking, where it is served as a warming side at family meals and celebrations.

This version builds flavour with garlic, thyme and Cheddar. Layering the potatoes with sauce helps them cook through while the cheese forms a browned top.

Nutrition and macros by portion

The nutrition label shows one serving as written: 3280 calories, 130g protein, 330g carbs, 170g fat.

The potatoes and flour supply most of the carbohydrates, while the butter, whole milk and Cheddar contribute much of the fat; the cheese and milk also provide protein. Serve a moderate slice with plenty of green vegetables to balance the plate.

Choosing the potatoes

Yukon Gold potatoes: these have a naturally buttery texture and hold their shape while becoming tender in the oven. Slice them evenly so they cook at roughly the same rate.

Onion: thin slices soften between the layers and add a gentle savoury sweetness. Keep them fairly fine so they do not remain firm after baking.

Getting a smooth sauce

Flour and butter: whisking the flour into the melted butter for 1 minute helps form the base of the sauce. Add the milk gradually and keep whisking to reduce the chance of lumps.

Milk and stock: pour them in steadily and whisk until combined before seasoning. The sauce will be poured over the potatoes, so aim for a smooth consistency rather than letting it thicken excessively in the pan.

Layering for even cooking

First layer: spread the potatoes across the base of the dish, then distribute the onion, sauce and 113 g of Cheddar over them. Repeat with the remaining ingredients to season and coat both layers.

Even slices: try to keep the potato slices similar in thickness and arrange them without large gaps. This helps the sauce reach the layers and the potatoes soften more evenly.

Checking texture and doneness

Covered baking: the first 30 minutes under foil give the potatoes time to cook in the sauce without the top browning too quickly. Keep the foil in place during this stage.

Golden top: bake uncovered for the final 40 minutes, until the cheese is melted and golden brown. If you are unsure whether the potatoes are tender, check a slice in the centre with a knife; it should pass through easily.

Serving the bake

Resting time: leave the dish to stand for 10 minutes after baking. This gives the sauce a little time to settle, making the portions easier to lift.

On the plate: serve alongside green vegetables, such as broccoli or green beans, or a crisp salad to bring freshness to the rich, cheesy potatoes.

Recipe notes & tips

• Use a sharp knife or mandoline to make the potato slices even.
• Grate the garlic finely so it mixes smoothly into the sauce.
• Whisk continuously as you add the milk to help keep the sauce smooth.
• Spread the sauce across both layers rather than leaving it in one spot.
• Let the finished dish rest for the full 10 minutes before serving.

Variations

• Add nutmeg: grate a small amount into the sauce for a warm, savoury note.
• Try another cheese: use a similarly melting cheese in place of some or all of the Cheddar.
• Use fresh herbs: swap the thyme for chopped rosemary or parsley to change the flavour.
• Add greens: layer in a small amount of spinach between the potatoes and onion.
• Make it more peppery: add extra black pepper to the sauce before layering.

Common mistakes to avoid

• Uneven slices: thick pieces may stay firm while thin ones soften; slice the potatoes evenly.
• Lumpy sauce: adding the milk too quickly can make lumps; pour it in gradually while whisking.
• Browning too soon: keep the dish covered with foil for the first 30 minutes.
• Firm potatoes: check a slice from the centre and continue baking until a knife passes through easily.
• Cutting too soon: the sauce may run when the dish is piping hot; let it stand for 10 minutes.

How to store

Refrigerate leftovers in a covered container for up to 3 days. Reheat in an oven at 180°C until piping hot throughout, or microwave individual portions until hot.

Frequently asked questions