In a large Dutch oven or pot over medium-high heat, add the oil and garlic and cook, stirring, until the garlic is golden and fragrant, about 2 minutes.
Add the piment d’Espelette and season with salt; cook for 10 seconds more, then stir in the clams, olives, wine, and sherry.
Bring to a boil, then cover the pot with a tight-fitting lid, lower the heat to medium-low, and simmer until the clams open, 10 to 12 minutes.
Uncover, remove and discard any clams that don’t open, and add ¼ cup of the parsley to the pot.
Stir to combine and transfer to a serving platter.
Sprinkle with the remaining ¼ cup of parsley.
Serve with crusty bread.
