How can I make Pacman muffins?
What makes pacman muffins different from any other muffins is only their decoration, not their content. So of course there are no special recipes for them. 

You should pick any recipe for iced muffins, or even pick two separate recipes, one for plain muffins and one for icing. Buttercream would be a good choice, as well as other soft types of icing. Then you have to color your icing yellow and black, and place it on the muffins in the desired shape. 

As it seems that you are a beginner in cake icing, some help would be good. Icing can be a messy process, and creating patterns is harder than plain icing. I would place a paper strip folded in the middle on the muffin to separate the yellow and black areas, and only remove it when both colors are done. Fixing with toothpicks may be helpful.