Heat 100g butter in a saucepan, add the onion, bay leaf and thyme cooking over a low heat stirring occasionally for 7-8 minutes.
Meanwhile bring the stock up to the boil in another pan. Add Risotto rice and sweat for 2 minutes.
Add a quarter of the white wine, keep stirring until the wine has evaporated. Repeat this process until all wine is absorbed.
Add a ladle of the hot stock and continue cooking until liquid absorbed.
Continue adding stock a ladle full at a time and continue stirring each addition until all the liquid has been absorbed. This will take 15-18 minutes.
When rice is almost tender, add frozen peas (defrosted). Check seasoning and turn down heat. Add Crab Meat, chopped chervil, lemon zest and juice. Add in the remaining 75g of butter beating vigorously. Check seasoning. Adjust if necessary. If the risotto is too firm, add a little more stock or white wine.