Butter or spray with non-stick spray an 13-inch by 9-inch baking dish. Set aside.

In a large glass mixing bowl, combine the marshmallows and butter. Melt in the microwave for 2-4 minutes on high. Check part way through and stir to combine with a silicon mixing spoon sprayed with cooking spray (keeps the marshmallows from sticking to the spoon).

In a second mixing bowl or container large enough to hold the cereal, combine the cereal and mini chocolate chips. Toss to mix together.

Pour the melted marshmallow mixture into the cereal and stir quickly (again with a silicon mixing spoon sprayed with non-stick spray) to fully combine. Spoon into the prepared baking dish and press down with the spoon.

Place the 2 ounces of chocolate into a small glass mixing bowl and heat in the microwave for 1 ½ minutes on 50% Power. Stir, and repeat for 1 ½ minute at 50% power until fully melted (or if almost melted at 1 ½ minutes, decrease the time for the second phase after stirring).

Using a dining spoon, hold a spoonful of the melted chocolate over the cereal bars and gently shake the spoon from side to side while moving it over the bars to make a light drizzle. Repeat until the bars are covered to your liking. Allow the chocolate drizzle to cool and harden before cutting (note: if made in warm temperatures, the pan may be refrigerated to hasten the chocolate hardening).

Cut into 2-inch by 1-inch bars.