Ravioli with apple, chestnuts, and wild boar

Ingredients

• 1 cup roasted, shelled, and skinned chestnuts; see how to roast fresh chestnuts ; (1/2 lb in shell or 7 oz bottled whole)
• 3 oz wild boar sausage, uncased (or 2 oz pancetta/bacon)
• 3 tablespoons unsalted butter
• 1/4 cup finely chopped onion
• 1 large garlic clove, smashed
• 1/4 cup water
• 1 Granny Smith apple
• 2 tablespoons finely grated parmesan
• 1 tablespoon finely chopped fresh flat-leaf parsley
• Pasta dough: 1/3 chestnut flour and 2/3 white flour; figure the usual number of eggs.