Heat butter. Add chopped onions. Stirfry for 2-3 minutes. Add tomato puree, bring to a boil. Pound together garlic, chilli powder, salt, clove-cinnamon powder. Add all ingredients except cornflour, simmer for 5 minutes. Mix cornflour in 1/2 cup water to make smooth paste. Add to the boiling sauce, stirring continuously to avoid lumps. Stir and cook till thick enough to spread on pizza bread. Cool, stirring occasionally, to avoid surface from drying up.