Preheat oven to 350. Line a 15x 10 jelly roll pan with parchment paper. Arrange crackers on the prepared jelly roll pan.
In a saucepan, combine brown sugar with the butter. Bring to a boil, then boil 1 minute. Remove from heat, and stir in vanilla.
Pour hot butter mixture over the graham crackers, spreading evenly. Sprinkle with the chopped pecans.
Place in oven, and bake 10 minutes. take out of oven, and cool slightly, about 5-6 minutes. Take a pizza cutter, and roll along the segmented lines in each square, creating 48 bars.
Next, place chocolate morsels in a microwaveable bowl. heat in microwave for 30 seconds, Take out and stir. Put back in microwave, and continue heating in 10 second intervals, until chocolate is smooth.
Drizzle melted chocolate over bars, then repeat the steps used with the milk chocolate, using the white chocolate. Let cool completely, before enjoying.