Gnocchi alla romana - Good Food Middle East

Ingredients

• 1.2l milk
• 250g fine semolina
• 115g butter, cubed, plus extra for the dish
• 125g grated parmesan or vegetarian alternative, plus extra to serve
• 3 egg yolks
• 2 x 400g cans plum tomatoes, drained and roughly chopped
• 75g butter
• 1 onion, peeled and halved