Step 1

Peel and slice the potatoes thinly, by hand or by using a mandoline or food processor.

Step 2

Use a little of the butter to grease a dish around 30 x 20 x 5cm.

Step 3

Arrange about a third of the potatoes in the bottom of the dish and pour over a third of the hot stock.

Step 4

Sprinkle over half of the onions, herbs if using and season with salt and pepper.

Step 5

Add the next third of potatoes and stock, the remaining onions, some herbs and seasoning.

Step 6

Finish with the last of the potatoes, stock and seasoning.

Step 7

Divide the butter into pieces and dot over the potatoes and bake for an hour at 200 C, 400 F, 180 FAN or Gas 6.