Pull lobster heads in half or place in a bag and crush with rolling pin into walnut-sized pieces. Heat 3 tablespoons of olive oil over medium-high heat in large fry pan. Add lobster shells and stir for 5 minutes, until slightly golden. Add brandy and carefully flambé shells to extract maximum flavour. Transfer lobster shells to a large stock pot. Heat remaining olive oil in same large fry pan lobster shells were cooked in. Add onion, carrot, celery and garlic and cook until vegetables have begun to soften, about 3 to 5 minutes. Transfer to stockpot and add remaining ingredients. Bring to just a boil and reduce to a simmer for 25 minutes. Don’t let the stock boil. Strain stock through colander into clean pan, pressing firmly on solids to extract any remaining liquid. Discard solids. Bring stock to a simmer and reduce lobster stock until yields about 8 cups. Strain through sieve.