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How to make a Lego Cake

How to make a Lego Cake

So what kind of Lego builder are you? Do you build sets, take them apart and build them again? My daughter loves to do that.

Or maybe you build them and since it took FOREVER you never take it apart and admire it forever. That is SO me!

But this post is not about that kind of Lego building habits. THIS post is all about BUILDING a beautiful Lego cake and enjoying the yummy thing!:-D

Let's dive in...


Key Materials

1. Marshmallow Fondant (MMF). In Red, Yellow, Green, and Blue (but OMG just imagine a pink, purple, and white block cake!! Sooo cute:-D) Make your own, there are a lot of simple recipes online!  Or use Wilton fondant in a pinch, whatever you do, I DO NOT recommend Satin Ice. This is a great fondant for many other purposes, however, for this project this fondant doesn't fill each cavity very well and lacks firmness to make clean pieces. 

2. The Mold. Get your mold HERE or make your own using a lego piece and craft silicone (see our youtube video here for some how to make details)

3. Lego-style Font template. Use a Lego-style font template to make a name plate Get our font template here.



4. Ganached cake. The cake in picture is a 1/4 sheet cake (9"x13") covered in chocolate ganache (smoothed with a bench scrapper). This gives you an extra block-y look. See gananche instructions on our post here.


The Steps

Step 1. Prepare Fondant. A few days before you want the finished cake mix your marshmallow fondant with your desired colors. 

  • I recommend starting with the lightest fondant color and working your way to the darkest (I do yellow, green, red, then blue).  This way you can keep from cross contaminating your fondant colors and save yourself from over washing/drying your hands. NOTE: If you make the topper you will also need black, white and extra red and yellow.
  • Let the fondant 'rest' overnight AFTER completely mixing colors it, by letting your fondant 'rest', it will dry/firm a little and make it a bit easier to work with
  • HOW MUCH of which color you ask? That depends on the look you want. I wanted a lot of yellow on top, wanted a lot of green for the board and very little blue.
  • Note: Get a rough idea of how many pieces you will need per color by estimating how many you will need to cover the top of your cake pan and cake board. (hint: try to envision how much fondant it will take to cover your pan) 
  • The size I used here was a 1/4 sheet pan (9" x 13") and for the look I wanted it required about: 
    • 50 green mold pieces
    • 23 yellow mold pieces
    • 13 blue mold pieces
    • 13 red mold pieces

Step 2. Prepare blocks (for top only) - NOTE: for a SHARP look prepare 2 days in advance.

  • Do this in advance to allow your pieces to dry and therefore create 'sharp' looking blocks. Drier fondant is sharper looking fondant and sharp looking fondant always looks cleaner and gives a more finished look. But if you are out of time last minute is OK too!!
  • Again, get a rough idea of how many pieces you need per color by estimating how many you will need to cover the top of your cake pan and cake board. (hint: try to envision how much fondant it will take to cover your pan)
  • For this 1/4 sheet (9" x 13") and for the look I wanted it required about:
    • 50 green mold pieces
    • 23 yellow mold pieces
    • 13 blue mold pieces
    • 13 red mold pieces
  • STICKY FONDANT NOTE: If your fondant is sticky try adding a dab of shortening, powdered sugar or corn starch 
  • NOTES ON HOW TO USE THE MOLD: Roll a 1" ball of fondant FIRMLY to get all of the creases out), push the ball into the mold cavity real well with your fingers (not a roller). Then using a sharp knife cut off the excess on TOP so that it is flush with the mold. If this gets to be too sticky rub a touch of powdered sugar on top before cutting the excess fondant. Then, bend the mold back with your fingers and pull / peel the fondant piece out of the mold slowly (do not use anything else but your fingers so as not to damage the mold or your piece). RE-SQUARE the soft pieces with a straight edge on a large flat surface dusted with powdered sugar.  
  • Let your pieces dry for a full day or two (minimum overnight). 
  • STORAGE NOTE: Store on trays or cutting boards in a dark area such a pantry or cabinet away from sunlight and bulb light to prevent them from fading or changing color. DO NOT store them in an air-tight condition, this will cause marshmallow fondant to sweat and stay soft. 
  • Once they are fully dry, cut the block pieces evenly into 3 smaller pieces.  DO NOT cut all the green pieces since you need a good amount of those for the cake board.



      Step 3.  Make the Name Plate Topper. While your blocks are drying and since you have just worked with all of your colors you can now use this fondant to make the name plate.

      • Using the block font paper template, cut out the pieces for your name plate. NOTE: A copy of the this font template is now included in all mold orders.  
      • Roll out the fondant colors, cut out your template letters, cut the name, the black, yellow, and the red and black backgrounds using a small sharp knife. Use shortening to adhere layers together. 

      Step 4. Prepare Cake. Bake and cool your cake completely.  Torte it by slicing down the center of the layer for the filling and then FREEZE. You can wrap or not (with plastic wrap or foil), this might depend on the types of other food items in your freezer. For instance I had a cake-only freezer so I never needed to wrap when storing short term. Short term freezing will incorporate more moisture into your cake so don't worry about it drying out:)! Short term might be less than 2 days or 2 hours...really depends on your freezer. 
      • When you are ready to start the decorating process pull the cake out of the freezer.  Next separate the layers carefully and fill with your desired filling.  
      • Use your chocolate ganache to coat sides and top of cake with a spatula.  If your ganache is too firm heat in the microwave for just a little bit and apply.  Use a bench scrapper to achieve nice clean sides and top.  Once your ganache is on if you want, to 'fix' the smoothness with the bench scrapper, heat a pot of water to dip and heat the bench scrapper.  
      • Refrigerate your ganached cake for about an hour to firm.  While this is refrigerating let's start the side blocks!

      Step 5.  Make Side Blocks

      • Roll out wide pieces of 4 different colors preferably using a pasta roller.  I use a kitchen-aid one that attaches to my mixer. NOTE: To get a thicker piece than the #1 setting, reverse it (back the knob up). It will work just as well and give you a thicker piece.  
      • Let your rolled out pieces dry preferably for about 1/2 hour to an hour.
      • While these are drying, create your cutting guide (or purchase ours here). Using graph paper or engineering paper draw lines using a straight edge using the same width and length of your small molded block pieces (the dimensions of the final piece after you have cut it into 3).  If you bought a mold these templates are now included with each block mold order!:).
        • AFTER the pieces have firmed from the drying, cut out these pieces using a small knife, a straight edge, and your paper guide. By having waited for the pieces to dry out this will go a lot faster:). 
        • These I like to cut as I decorate, I found these hard to estimate quantity.

        Step 5. Put it all Together!!

        • Ok so this is what I think is the fun part!  Apply a thin film of shortening to get your block pieces to stick.  I like to use shortening because you can move your pieces around later if it needs tweaking.  
          • Next, start playing building blocks!  Create your own block color pattern on top of the cake.  
          • Overhang the border blocks just a tad so the side pieces will meet flush just under them.
          • Match the side pieces of the first row to the border pieces with the appropriate color.  
          • Cut side pieces where necessary. Match accordingly working from the top down and use a straight edge to align as needed
          • Fill the remaining rows of the side freestyle!
          • Apply green pieces on the board by using sugar glue. Simply make this with the following steps:
            • 1 part tylose powder, 1 part granulated sugar and 4-5 parts super hot water
            • Let sit for 15 minutes to set
          • After it is all together cut the cake board to fit (so no cardboard is showing beyond the green board pieces) and place the name topper on the cake.

          Whew, if you did all that CONGRATULATIONS!!

          FUNNEST. CAKE. EVER. :-D

          I know it is a TON of work but your little one (or big one) will LOVE it! 


          Happy Lego Cake Making!!



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