Heat the olive oil in a large saute pan (preferably one that can also be used for serving) over high heat. When it begins to smoke, add the chorizo and cook until just beginning to color, 2 minutes. Add the onion and red pepper flakes and cook, stirring, until the onion is translucent, 2 minutes.
Add the garlic, cockles, clam juice and wine. Reduce the heat to medium and cook until the cockles are open and warmed through, 5 to 7 minutes. (Discard any cockles that do not open.) Remove from the heat and stir in the butter and parsley. Season with salt and pepper. Serve with bread.