To prepare a trufas de chocolate negro dark chocolate truffles recipe, first you need to prepare your ingredients. First, you'll need your chocolate. You can buy chocolate at most grocery stores, or you can make it at home. To make the chocolate: Melt chocolate in the microwave for 30 seconds or until melted. Then, stir in your cocoa powder until it's completely dissolved, then add your vanilla extract, and stir until the mixture is completely combined.