Melt white chocolate chips. This can be done over a stove top using a pan with water in it and a smaller bowl on top with the chips, or use an instant pot with 2 cups water over heat and a smaller bowl on top containing the white chocolate chips. Or the chips can be melted in a microwave, stirring often to make sure you do not over-heat them.
Add shortening, coconut oil or vegetable oil and stir chips. The boiling water will heat the bowl the chips are in and melt them. Stir and allow to melt.
Keep bowl over hot water to keep chocolate melted and smooth.
Dip Nutter Butter Cookies into chocolate and place on a cooling rack or wax paper. Add candy eyes and allow to cool and set up. For Ghost cookies dip the entire cookie in the white chocolate.
For Mummies, dip 3/4 of the cookie in the white chocolate, pour remaining melted chocolate into a zip lock bag and snip the corner of the bag. Then drizzle white chocolate over cookies to look like strips of rags covering mummy cookies. Or use a fork and drizzle the chocolate on the cookie to look like a mummy.
Allow to cool and set up. Enjoy. Store in a container.