Heat a large heavy-based saucepan and melt the butter. Add the onions and garlic and cook until browned. Add the carrots, capsicum and anchovies cook until softened but not brown. Season. Add the tomatoes, vegetable stock, water and basil and reduce the heat. Simmer for around 20 minutes, stirring occasionally. Remove from the heat and use a stick mixer to blend the soup until smooth. Stir in the cream and serve immediately.