Melt the chocolate in the top of a double boiler set over barely simmering water, stirring frequently. When melted, remove from the heat and mix in the peanuts and raisins. Drop the mixture by the spoonful onto a sheet pan lined with parchment paper or a nonstick baking mat, or pour into a buttered loaf pan lined with plastic wrap. Let set at room temperature until firm and completely cooled. If using a loaf pan, cut up into squares. Store in an airtight container.