Meanwhile, heat olive oil in a skillet over medium heat. Add garlic and cook until fragrant, about 2 minutes. Add wine and scrape up any browned garlic from the bottom of the pan. Cook for 2 minutes. Add clam juice and turn heat to medium-high. Simmer, stirring occasionally, until reduced by half, about 10 minutes. Add pepper to taste. (I find it won’t need salt with the saltiness of the clams.) Add parsley and butter and stir until butter melts.