Preheat oven to 180°C or 160°C fan-forced. Spray a 6-cup Texas muffin tin with oil and set aside. Spray oil in a frying pan; over medium heat, cook the onion and bacon until the onion is translucent. Push the bread into the muffin tin and spoon in the bacon and onion mixture. In a bowl, whisk together egg, milk and parsley and distribute evenly into the 6 muffin tins. Bake for 20 minutes. Leave to sit for 3 mins before running a knife around the edges