This chocolate cage was made from a combination of white chocolate, milk chocolate, and dark chocolate. I know candy melts are used for cages sometimes, but I wouldn't recommend them because the candy dries too hard and would be more prone to cracking. Stick to real chocolate.
This cake was baked using the white sour cream cake recipe and is four eight-inch layers. The texture of this cake makes multiple layers stack well. It is frosted with classic vanilla buttercream.
There are many tutorials on pinterest for making a chocolate cage. I recommend reading several of these to get all the information you can before making your first attempt. Start by measuring the circumference and height of the cake. Cut of piece of parchment paper the size of the measurements, plus a couple of inches. By adding to the height, the cage will extend higher than the cake. The circumference can be tricky, though. If the parchment is cut exactly to the measurement of the circumference, the finished cage will not reach around the cake. Because of the thickness of the chocolate on the paper, the parchment needs to be longer by an inch or two. How do I know? Trial and error.
Spread the parchment out on a flat surface. Melt the different chocolates and fill decorating bags. Snip the ends off the bags. Start with the dark chocolate, as it takes a bit longer to dry. Make random designs on the parchment paper, filling the paper. Follow with the milk chocolate, then the white chocolate, overlapping the design. Let the chocolate dry until it firms up. It will begin to lose its sheen when it is dry. This takes around 30 minutes. When the chocolate is dry and firm to the touch, apply the chocolate sheet to the side of the cake with the parchment paper on the outside. Press it gently into the frosting, so that it adheres. Refrigerate the cake for about 5 minutes, then carefully peel the parchment paper away. The cake is now enclosed in a chocolate cage.
The strawberries on top of this cake were washed, dried, and drizzled with the same melted chocolate that was used to make the cage. When the chocolate is firm on the strawberries, place on top of the cake. Use a small dollop of buttercream underneath the strawberries to add height and to adhere them to the cake.