In a large bowl, combine cereal and diced Reeses. Set aside.
Spray a 8 x 8 in. pan with cooking spray and set aside.
In a large pot melt butter over low heat.
Add karo syrup and marshmallows and stir continuously until mixture is smooth.
Remove from heat and add cereal mixture into the pot and fold together just until cereal is evenly
coated.
Press mixture into the 8 x 8 in.pan. Set aside.
In a small microwave safe bowl, add peanut butter.
Microwave for 30 second to a minute to melt.
Set aside to let cool slightly.
In a separate small microwave safe bowl, melt chocolate at 30 second intervals, stirring between intervals, until smooth.
Set aside to let cool slightly.
You can either drizzle the peanut butter and the chocolate over the treats or pour over the top and swirl around.