Prepare sandwich cookies by putting 1 T of peanut butter between two Ritz crackers.
In a double boiler, melt the milk chocolate baking chips over medium heat, stirring until completely melted and smooth.
Reduce heat to a very low simmer and dip sandwich cookies in chocolate until completely covered. I use tongs to flip them over several times in the melted chocolate.
Place the cookies on wax paper covered cooling racks and allow them to set (approx. 4 hours). I recommend placing them in the refrigerator to set faster.
Once you have used all of the milk chocolate, add the dark chocolate chunks to the double boiler, increase heat, and stir until melted and smooth.
Reduce heat and dip remaining sandwich cookies in dark chocolate. Allow them to set on wax paper covered cooling racks.
These will keep in the refrigerator, in an air tight container, for several weeks.