Add the oil, onion and garlic to a multicooker, and cook on the 'fry' setting for around 4 minutes, stirring once or twice, until soft and golden brown.
Turn the machine off, and add the cream cheese, milk, pesto, chopped sun-dried tomatoes, olives, and salt and pepper. Add half of the grated mozzarella, and mix well until the residual heat in the pan has melted the cream cheese and created a sauce.
Add the uncooked fresh tortellini, and mix well to combine. Top with the remaining mozzarella, and close the lid. Cook on the 'bake' setting for 30 minutes. Serve warm.