Growing up we always had a cake on our birthdays. My mom would always made us wonderful birthday cakes that she would decorate. To me birthdays=cakes. So every year I have made a cake for Lucas' birthday. He has had a firetruck, Thomas, construction site, Airplane/helicopter, and now this year the Lego cake!
What I used:
12 X 18 Sheet Cake (3 boxed cake mixes)
My make-shift circle cutter
3 1/2 tubs of frosting
The KEY to this cake is freezing. I made the cake Friday night, and when it cooled I cut it like this
I looked at one of Lucas' Lego's and figured out basic size proportions and then I just did my own thing. I cut the long blocks 3" by 6", the squares were 3 X 3 and then I had some 1 1/2" X 3 and 1 1/2" X 6.
You really could make them any size, it is just the proportions that matter. If you were making this with a 13 X9 cake you might want to make them smaller. I also had some extra pieces that I used for the circle knobs on top.
After I cut it as shown above, I put the pieces into about 6 different gallon size freezer bags and threw them in the freezer. I stacked them all neatly on top of each other and they all survived just fine.
The next day I pulled all the cake out, and I think I waited at most about 20 minutes and then began cutting. Cakes usually mound in the middle, so I cut off the bottom of several of the pieces of cake to try and level them out a bit. This is so easy to do when the cake is frozen.
For the tops of the Lego pieces, I have heard about people using marshmallows, or even rolls of fondant (both which would have probably been easier), but I am a bit of a cake purist, I mostly just like cake and frosting on my cake.
So I used some of the extra cake and sliced it in half, to make it not so thick. I then created my own circle cutter. I used card stock and formed it into a circle. I used my spaghetti size server thing to get a nice circle (FYI-I used the number 2 hole). I taped my little creation and then punched out pieces of cake. Most of them got stuck in the end, so I simply used the handle of a butter knife to push them out.
Then I figured out my layout. As you can see some of the pieces are a bit round still, some I leveled off more, and some I just said, forget it, I just wanted to get this thing done. After figuring out my layout I took a picture, which I referred back to when I was frosting so I was very happy to have it. Also, at this point I put the little circles in a freezer bag and put them back in the freezer (A DEFINITE MUST)
Then the frosting began. Again, the cake being frozen is the key, other wise if you tried to frost the raw sides it would just be a crumbly mess; as you can see there were some small crumbs anyway. After I got the big bricks all frosted, I pulled my circles out of the freezer. I found it was easiest to frost each circle and then put it on the big bricks. Looking back, I wonder if it might have been easier to use frosting in a bag with a big open tip and just squeeze it onto the little circles after they were on the cake.
Three hours later, I was finally done with the cake. I was a mess, but Lucas and everyone else loved it, so it was worth it.