Combine the butter, powdered sugar and peanut butter in the bowl of an electric mixer fitted with a paddle attachment.
Mix on low speed until well combined. (If you have no mixer this can be done by hand).
Then mix in the toasted rice cereal.
Using your hands, form into ½-ounce balls (the size of a large marble) and refrigerate until firm (about one hour).
Place the white chocolate in a microwave-safe bowl. Melt, adding vegetable oil part-way through.
After all chocolate is melted, stir until smooth.
Dip the balls, one at a time into the melted white chocolate mix, using a fork to roll them around so they are entirely coated then remove them from the chocolate and set on a waxed paper lined sheet pan.
Chill to set up about 30 minutes.
Separate remaining white chocolate into two bowls and add one to two drops of food coloring to each to tint each bowl a different color.
Reheat chocolate if necessary and, using a small spoon, place a dollop of the colored chocolate on the eyeball to make an iris.
Use a smaller drop of the contrasting color for the pupil.
Let the chocolate set, place balls in individual mini muffin papers and serve.