Line a baking sheet with foil. Add ⅔ of the chocolate chips in a heavy medium saucepan over low heat until melted and warm (not hot) to touch. The chocolate should be heated to 113 to 120°F, not exceeding 120°F.
Take the bowl of melted chocolate off the heat and stir in the remaining chocolate chips, combine until smooth. Allow the melted chocolate to come between 78 to 82°F. You can place the bowl of melted chocolate over a bowl of ice water to speed up the chilling process.
Pour chocolate onto foil; spread to ¼-inch thickness (about 12x10-inch rectangle or 9x9-inch square pan). Sprinkle with M&M candies, caramel popcorn, peanuts, and mini candy, making sure all pieces touch the melted chocolate to adhere.
Put white chocolate in a heavy small saucepan. Stir continuously over very low heat until chocolate is melted and warm but not to exceed 110°F. Remove from heat. If chocolate is not able to drizzle easily with a spoon, add some vegetable shortening and stir until smooth, about a ¼ teaspoon at a time, until the desired consistency is reached. You want to be able to drizzle the white chocolate.
Dip a spoon into the chocolate and drizzle from side to side over the bark to create zigzag lines.
Chill candy bark until firm, about 30 minutes. Slide foil with candy onto a work surface and peel off the foil. Cut bark into irregular pieces.