Set up a double boiler to melt the chocolate. Here are some different ways to do this:
Boil water. Place chocolate chips into a stainless steel mixing bowl, then place the mixing bowl inside a wider shallow bowl or pan. Pour boiling water into the shallow pan and stir chocolate with a rubber spatula until completely smooth and completely melted.
Heat a large saucepan filled with water over high heat until boiling. Reduce heat to a simmer. Set a heat-proof bowl over the simmering water. Add chocolate chips and stir with a rubber spatula until smooth and completely melted. Remove bowl from heat.