M.M.
A 2yr old will be very excited at any cake you put in front of him with candles. Save the really tricky time consuming cakes for the next few years. How about buying or making a rectangular chocolate cake, covering it with brown icing and then using a toy truck or two on top. You could use the icing pens to draw white lines like a road on top and maybe a toy stop sign. I did something similar for my son's B'day cake. He loves 'diggers' so I had 2 tiny tonka excavator's on top of a brown iced cake and then used different brown colored brownie chunks as the piles of dirt the diggers were pushing around. Big hit. If you can find the toy trucks at e.g dollar store then buy a truck for every kid at the birthday party/dinner.
Enjoy the party ! little kids are so funny to watch at B'days.