I made the cupcakes and frosted them with white whipped frosting + yellow food coloring gel.
My husband took over with the Batman logo - I bought a package of those soft Dutch cocoa sugar cookies. Next, he used a measuring cup and a pairing knife to get the logo just right...
Now onto the cake for the family party - I made a box cake mix (added some of my own ingredients to make it a bit homemade) and baked in two 9" rounds. All of the colors shown on the cake (gray, blue, yellow) were made with white whipped frosting and food coloring gel mixes. The black was premade icing from the store. We picked up the Batman figurine at Toys R Us for about $7.
The city scape on the side of the cake took longer than expected, but it wasn't impossible. I made my own piping bags out of Ziplocs with a tiny hole cut at the bottom. I piped the outline of the city and then filled it in. The yellow "windows" were my husband's idea, and I think they made the cake work. Instead of piping a frosting edge at the base of the cake, I just poured chocolate chips around the edge to fill in the gap between cake and plate. It better resembled a pavement or road - not intentional, but it definitely worked.