Penne pasta with Napoletana sauce and ricotta

Ingredients

• 500 gram penne pasta
• 1 tablespoon olive oil
• 1 onion, finely chopped
• 2 garlic cloves, thinly sliced
• 1/2 teaspoon dried chilli flakes
• 2 x 400g cans diced tomatoes with basil and garlic
• 1/2 cup water (see recipe tip)
• 150 gram ricotta, crumbled
• 1/2 cup pitted assorted olives
• 1/2 bunch parsley, chopped