• For the pastry
• Preheat oven to 200C/400F. If you have a food processor, add flour, salt and butter and process until you have a fine crumb. Alternatively add to a large bowl and rub the mixture between your fingers to break up the butter into small pieces. You should still have small pieces of butter throughout the mixture.
• Add eggs, milk. Process until a ball forms. If using your hands, miss with a wooden spoon then knead with your hands until incorporated. Roll out dough between sheets of baking paper. Place in the fridge until firm. About 15 minutes.
• Grease tart tin with softened butter and line with pastry. I used a 30cm tart tin with a depth of 4cm. Line with baking paper and fill with weights. Bake for 15 minutes, remove weights and cook for a further 10 minutes or until lightly golden. Set aside. Lower heat to 180C/350F.

For the caramelised onions

• While your pastry is resting and cooking, add onions, butter and oil to a large frying pan and cook over medium-low heat until golden and caramelised. Stir often for about 40 minutes. Add balsamic vinegar to deglaze pan and cook for a further minute. Add to the base of the pastry shell.

For the filling

• In a large bowl add eggs, cream, milk, parsley, parmesan, salt and pepper and combine. Add egg mixture over the onion mixture until almost the top of the pastry shell. Nestle the tomatoes into the mixture and add dollops of fresh ricotta.
• Bake for 50 minutes or until just set and golden on top. Rest for 10 minutes and serve with a good drizzle of balsamic vinegar.