Remove the 'face' from your peep marshmallows.
Cut up your butter and add to your pan. If you're using a nonstick pan you don't need to grease it, but if you're using another type spray it with cooking spray.
Add the butter and peeps to your stovetop pan. Keep 3-6 peeps back initially. Keep the heat under the pan low, you don't want to rush the butter and marshmallows melting as that will give them a harder consistency. If you add more towards the end of the melting time the color will be a bit stronger.
Add your final peeps and allow to melt. Once the peeps have all melted remove from the pan and add your rice krispies, combine.
Using a spatula (I recommend a silicone one) gently press the treats into a greased 9x13, or an 8x8 if you want thicker treats.
After they've cooled, if desired, use your cookie cutter to press into the baked treats and form peep shapes.