Fry the onion in a large pan over medium heat until translucent.
Add the garlic and peppers and stir-fry some more.
Add the chicken cubes and fry until golden, adding more oil if necessary.
Add some salt and pepper to taste, tomato paste and both types of paprika.
Add the sliced mushrooms if you are using them and let the pan come back up to heat.
Add the peri-peri sauce and stir through. Once the sauce starts to bubble, lower the heat and add the cream. Thin down with water if necessary.
Let the chicken and sauce simmer on low heat for about 10 minutes, stirring occasionally. The sauce should thicken slightly and all the chicken cubes should be cooked through.
Add a squeeze of lemon juice to the pan and scatter some chopped parsley over before serving on rice, pasta or crusty bread. Keep some extra Nando's sauce ready for the addicts!