Add the lobster meat and cook for 1 to 2 minutes. Remove from the heat. In a risotto pan over medium heat, melt the remaining 1 Tbs. butter with the olive oil. Add the fennel and cook until tender, about 5 minutes. Add the remaining 1/2 cup (2 oz./60 g) leeks and cook until tender, about 2 minutes. Add the garlic and cook for 1 minute.
For the risotto: Melt the butter in a large saucepan over medium heat. Add the shallot and cook until they are softened, about 3 minutes. Add the garlic and cook until fragrant, 1 minute. Add the rice and stir with a wooden spoon to combine the onion mixture with the rice. Add the wine and simmer until the liquid is evaporated.
In a sauté pan over medium heat, melt 3 Tbs. of the butter. Add 1 cup (4 oz./125 g) of the leeks and cook until tender but not browned, about 5 minutes. Add the cognac and simmer for 1 minute, stirring to scrape up the browned bits. Add the lobster meat and cook for 1 to 2 minutes. Remove from the heat.
Add cream and stir until rice mixture thickens, about 3 minutes. Add paprika and cayenne pepper; stir well. Add sherry and mix well. Stir lobster meat into rice mixture and cook until heated through, about 3 minutes. Mix Parmesan cheese into rice mixture until melted. Add onion mixture and mix well; season with salt and pepper.