Step 1
Preheat oven to 350 degrees F (175 degrees C). Line a rimmed baking sheet with parchment paper.
Step 2
Combine eggs sugar and vanilla sugar in a bowl and beat with an electric blender until foamy. Add oil and orange soda and stir to combine.
Step 3
Sift flour and baking powder together and slowly stir into batter until well combined. Spread batter on the prepared baking sheet.
Step 4
Bake in the preheated oven until a toothpick inserted in the center of the cake comes out clean about 30 minutes. Remove from oven and allow to cool completely about 1 hour.
Step 5
Sort chocolate-covered candy by the colors in your food color assortment such as yellow green orange blue and red.
Step 6
Cut cooled cake into evenly sized rectangles about 1.5 x 3 inches in size like oversized LEGO® pieces. Gauge the size in relationship to the chocolate-covered candy pieces; 8 pieces should fit onto each to resemble a large LEGO® piece.
Step 7
Mix about 1/2 cup confectioners sugar with enough lemon juice in a bowl to make a thick icing. Color with a couple drops of food coloring so icing turns a deep color. Brush icing onto 2 or 3 cake pieces and arrange 8 chocolate-covered candy pieces with the matching color on top. Allow to set.
Step 8
Continue with the next color and the next set of chocolate-covered candy pieces in the same color until all cake pieces are decorated. Allow to set.