Place the tomatoes in a roasting pot and add the Balsamic, olive oil, sugar, and salt. Stir to combine and place on the grill for 25-30 minutes until the tomatoes are broken down and have started to caramelize.
In a large pot, sauté the onions in some olive oil until they are translucent and fragrant. Add the garlic and basil and fry for another minute.
Add the roasted tomatoes, tomato paste and sugar. Stir to combine all the ingredients and pour in the stock.
Lower the heat and cover the pot. Allow to simmer for 10 minutes.
Remove the pot from the heat and blend the soup
Add the cream and season to taste.
To make the grilled cheese sandwiches. Add the cheese to 2 slices of bread.. Butter both sides generously.
Cook on the grill, over medium heat until the cheese is melted and the sandwiches are golden brown on both sides.
Serve the tomato soup with a swirl of cream and fresh basil leaves with the grilled cheese.