Tear or cut the prosciutto into bit-size pieces. Melt one tablespoon butter to a large pot over medium high heat, add prosciutto, cook until crisp, remove from the pot and set aside.

Drain the oysters, reserving liquid. Chop into small pieces.

Melt remaining 4 tablespoons butter over medium-high heat in the large pot. Add the onions and celery, saute until tender, about 5 minutes. Whisk together the reserved juice from the oysters and the cornstarch, stir into the onions and celery. Add the light cream, parsley, and Tabasco, bring to a slow simmer. Add the chopped oysters, and continue to cook until heated through and thickened, about 1 minutes. Serve topped with the crispy prosciutto.