Peel the potatoes and cut into fine slices, no thicker than a £1 coin and preferably thinner. Mix the milk and cream. Grease a 23cm x 23cm gratin dish with butter.
Melt ¾ of the butter in a frying pan and add the onions, garlic and rosemary. Cook over a gentle heat for 10 minutes, until soft and sweet, but not brown. Add the chopped anchovies to the pan and stir for a couple of minutes until the fillets have dissolved into a paste and mingled with the onions. Don’t let them burn or they will be bitter. Stir in the lemon zest and cayenne and add half the milk and cream mixture. Heat for a minute or two, then put to one side.
Layer a third of the potatoes in the bottom of the greased gratin dish, then spoon half the onion and cream mixture on top. Cover with another third of the potatoes, then with the remaining onion mixture. Season between the layers — you will probably need salt as well as pepper despite the salt in the anchovies; the potatoes suck up a lot. Finish with a layer of potatoes, then pour the remaining cream and milk mixture over the top.
If you are cooking the gratin in the same 160C/Gas Mark 3 oven as the lamb, add it about an hour before the end of the lamb cooking time.
Cook until the slices are easily pierced with the tip of a knife. Then, when you’ve removed the lamb, turn up the heat to 220C/Gas Mark 7, scatter the gratin with the breadcrumbs and the remaining butter and give it another 20 minutes.
If you have two ovens, heat to 200C/Gas Mark 6 and cook the gratin separately for 30 minutes, then add the crumbs and butter, reduce the temperature to 180C/Gas Mark 4 and cook for 30 minutes more. Leave to cool for 5 minutes and serve.
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|Serving Size: 1 Serving (306g)|
|Recipe Makes: 6 Servings|
|Calories from Fat: 248 (54%)|
|Amt Per Serving||% DV|
|Total Fat 27.6g||37 %|
|Saturated Fat 16.5g||83 %|
|Monounsaturated Fat 7.6g|
|Polyunsanturated Fat 1.6g|
|Cholesterol 92.7mg||29 %|
|Sodium 464.3mg||16 %|
|Potassium 850.7mg||22 %|
|Total Carbohydrate 47.3g||14 %|
|Dietary Fiber 5.7g||23 %|
|Sugars, other 41.6g|
|Protein 9.4g||13 %|
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Calories per serving: 462
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