Roasting white chocolate gives it a more complex, nutty flavor and beautiful caramel hue. To make it, spread 8 to 16 ounces chopped high-quality white chocolate on a large, smooth, rimmed baking sheet. (Be sure to use white chocolate with at least 30 percent cocoa butter, such as Ghirardelli or Lindt baking bars. Chips, lower-quality brands or "white candy coating" won't work.) Bake in a 250° oven until chocolate begins to melt, about 10 minutes. Stir well with a rigid spatula, then smooth out evenly. Repeat the stirring and smoothing every 8 to 10 minutes, until chocolate turns a deep caramel color, 40 to 50 minutes total. Don't panic if the chocolate appears grainy--just keep scraping and stirring at regular intervals. It will melt eventually with only a tiny lump or two remaining. To store: Transfer roasted white chocolate to a sheet of parchment paper and spread evenly. Chill until firm. Chop into pieces. Store at room temperature and use like chocolate chips, or remelt it for recipes.