Gnocchi with Gorgonzola and walnut sauce

INGREDIENTS
knob of butter
1 onion, finely chopped
75g (21⁄2 oz) walnuts, roughly chopped
1 tbsp plain flour
450ml (15fl oz) milk
125g (41⁄2oz) Gorgonzola cheese
salt and freshly ground black pepper
500g packet ready-made gnocchi
handful of basil leaves, to garnish (optional)

METHOD
In a pan, melt the butter over a low heat. Add the onion, and sweat gently for about 5 minutes until soft and translucent. Now add the walnuts, and cook for another couple of minutes. Remove from the heat, and stir in the flour, then add a little milk. Return to the heat, and add the remaining milk, stirring constantly for 4–6 minutes until the sauce thickens.
Remove from the heat again, and stir through the Gorgonzola. Season with salt and pepper.
In a separate pan, cook the gnocchi in plenty of boiling salted water for a few minutes, or according to the packet instructions. Drain well. Add to the sauce, and stir through well. Garnish with the basil leaves (if using), and serve immediately.