I found wonderful inspiration for my son's 3rd Birthday cake from this site. Thank you all for your ideas for a Cars 3rd Birthday Cake .
My son loves the movie "CARS" and he and I were looking at cakes on this site. We came across a couple that we liked and I modified the ideas to fit my very basic cake decorating skills.
I used 2 box mixes (chocolate and yellow) for a layered cake and used a simple premade vanilla frosting that I could color green with food coloring.
I baked both cakes to box specifications using a slightly larger cake pan than the traditional 9x13 to make the layers a bit thinner. Once baked and cooled, I frosted the top of the chocolate layer then put the yellow cake on top. I frosted the sides of the layered cake with the vanilla frosting saving some for the top that I colored green for grass.
With the tip of a knife, I drew the "3" in the green frosting. It was easy to correct if I messed up or got the sizing wrong by smoothing it out again. Once I was happy with the "3", I lined it with M&M's (my son's favorite candy). Once lined, I had my area in which to sprinkle Oreo cookie crumbs for the road. I found this easier for me than using another colored icing. I was careful to sprinkle a little at a time so as not to go out of my M&M line.
Once the road was completed, I placed some cars from the movie on to the road and in the grass. I made race signs and flags with markers and attached them to cut up drinking straws.
My son didn't get to see the finished cake until we were at the restaurant that evening. He absolutely loved it and didn't know what to say! It was a huge hit and my family couldn't believe I had made it myself.