Kale, onions and chestnuts - River Cottage

Ingredients

• 250g plain white flour
• 250g strong white flour
• 1½ level teaspoons fine sea salt
• 1 teaspoon easy blend (instant) yeast
• 1 tablespoon rapeseed or olive oil, plus a little extra
• About 300g kale or cavolo nero, leaves stripped from stalks and cut into ribbons
• A dash of extra virgin olive oil, plus extra to trickle
• 25g butter (optional)
• 3 onions, finely sliced
• 3 garlic cloves, sliced
• 200g cooked peeled chestnuts (vacuum-packed are fine)
• Sea salt and freshly ground black pepper