In a large microwave safe bowl, combine the cereals, pretzels, and pecans.
In a small microwave safe bowl, melt the margarine or butter. Stir in the brown sugar, cinnamon, nutmeg, and ginger until dissolved. Microwave for about 1 minute and stir again until smooth. Pour over the cereal mixture and stir to coat evenly.
Microwave cereal mixture for 3 minutes, stirring after each minute. Stir in the graham cracker pieces, and microwave 1 more minute. Spread evenly over waxed paper to cool.
In a small microwave safe bowl, microwave white chocolate chips and shortening for about 1 minute. Stir after 30 seconds. Once smooth it is ready, be careful to not overheat or it will burn. Drizzle over the snack mix, let it cool until chocolate is hardened. Break into pieces. Store in a sealed container.