For the lobster: Bring a large pot of water to a boil.
Add the lobsters and cook until cooked through, 8 to 10 minutes. Remove from the boiling water and allow to cool to the touch.
For the leek sauce: Saute the leeks in the butter in a 12-inch cast-iron pan over medium heat until tender but still green in color, about 5 minutes. Add the whipping cream. Season with salt and pepper and reduce at a low boil until the liquid almost evaporates and a thick sauce forms. Reserve, keeping warm.
Back to the lobster: Break the lobster down into its parts—claws, tail and body. Remove the meat from the claws and tail, and reserve. Break the bodies down into smaller pieces.
Add the broken down pieces to a 12-inch cast-iron pan (reserve the tail and claw meat) along with the butter, celery and onions and heat over medium-high heat. Cook until the celery and onions have softened, about 5 minutes. Deglaze with the bourbon and white wine. Add the heavy cream and 1 cup water and allow to reduce for about 7 minutes. Carefully pour the mixture into a blender, shells and all, and blend until fully combined.
For the leek sauce: Pour the lobster mixture through a chinois or very fine mesh strainer into the sauteed leeks. Add the scraped vanilla and bourbon and stir to combine. Taste and adjust the seasoning. Just before serving, mount the sauce with the white chocolate, stirring until just melted.
Slice the tail meat into medallions. Put all the lobster in the bottom of a wide serving bowl. Top with the sauce.
When blending hot liquid, first let it cool for five minutes or so, then transfer it to a blender, filling only halfway. Put the lid on, leaving one corner open. Cover the lid with a kitchen towel to catch splatters, and pulse until smooth.