Melt the butter in a medium size pot over medium-high heat. Add the leeks and cook for 10 minutes, or until soft and translucent but not brown. Add the garlic and cook until fragrant, one minute more.

Add the brandy and sherry and cook until the volume is reduced by half. Then stir in the tomato paste, old bay seasoning, and stock. Bring to a boil. Add the shrimp and turn off the heat. Let stand until shrimp are cooked through, about 5-10 minutes.

If you want a completely smooth texture, transfer the entire soup to a blender and add the cream cheese (or use an immersion blender) and puree until evenly smooth. Otherwise, reserve half of the mixture, blend half until smooth then add the reserved soup and pulse to chop it slightly. Taste and adjust with salt and pepper, as desired. Garnish with sour cream, if using and fresh parsley.