Preheat the oven to 250 F. Place the chopped chocolate into a glass dish in a shallow layer, and pour the vegetable oil on top. Place the chocolate in the oven for 10 minutes, then stir it with a rubber spatula. Continue to bake the chocolate, stirring after every 10 minutes, until the chocolate is a beautiful dark gold color and smells caramelized. The total baking time should be about 70-90 minutes—the exact time will depend on the chocolate, your oven, and the dish you're using, so use your eyes and nose as a guide.
During the baking process, the chocolate will at times look grainy and unappetizing, but as you continue to bake and stir it, it should loosen up. Different brands of chocolate behave different, and it is possible you may need to add a touch more oil to get a smooth consistency toward the end of the process.
Remove the chocolate from the heat. Scrape it into a bowl and add a nice pinch of salt, stirring it in and adding more to taste if necessary. At this point it can be covered and saved for the next step in a day or two, or you can proceed to make the ganache immediately. If you are keeping it, the caramelized white chocolate will eventually solidify at room temperature, so you will end to microwave it gently to get it liquid again before proceeding.
Pour the heavy cream into a small saucepan and place it over medium heat. Heat the cream until it starts to simmer and small bubbles appear all along the sides of the pan. Pour the hot cream over the caramelized white chocolate and whisk them together until shiny and smooth. Let the filling cool to room temperature while you prepare the candy molds.
If you want to add striped decorations to your truffles, microwave the white or light chocolate candy coating until melted. Transfer it to a paper cone, piping bag with a small round tip, or plastic bag with a small hole cut in the tip. Pipe a few lines across each cavity of the mold, and repeat with as many colors as you'd like to use.
Place the chocolate candy coating in a microwave-safe bowl and microwave it until melted and smooth, stirring after every 30 seconds to prevent overheating. Spoon the chocolate coating into the cavities of the chocolate mold. Tap the mold gently against the countertop to remove any air bubbles. Let the chocolate sit at room temperature for several minutes, so that the chocolate thickens and just starts to set around the edges. Then, turn the mold upside-down over the chocolate bowl or a piece of parchment paper and let the excess chocolate coating drip out of the mold. Use a large chef's knife, a bench scraper, or the side of an offset spatula to scrape the top of the mold clean and remove any excess chocolate. Refrigerate the tray to set the coating completely, for about 10 minutes.
Carefully spoon the caramelized white chocolate ganache into the cavities, making sure to leave room at the top for another layer of chocolate. Make sure that the temperature of the caramelized white chocolate ganache has cooled down until it is barely warm, so that it doesn't melt through the coating.
Refrigerate the mold to set the filling, for about 10 minutes. Once set, spoon more chocolate candy coating on top of the filling to seal in the ganache. Scrape across the top of the mold again to remove excess chocolate from the top and sides of the candies. Refrigerate the molds once more to set the chocolate completely.
When you are ready to unmold the truffles, gently bend the mold to loosen the chocolates. Turn the mold out onto a sheet of parchment and flex it so that the chocolates drop out of the cavities. These Truffles can be kept at room temperature for 3-4 days, or in the refrigerator for up to 2 weeks. For the best taste and texture, serve them at room temperature.