To a cold, small saucepan, add the olive oil, chopped pistachios, sliced shallots, and sliced garlic. Set over medium-low heat. Cook, stirring frequently, as the oil gradually comes up to temperature and bubbles consistently. Maintain a gentle simmer for 10–12 minutes, until the moisture cooks off and the shallots, garlic, and pistachios turn a light golden yellow. Remove the pan from the heat immediately.