Use a round cookie cutter, or glass to cut circles the size of the bottom of the muffin/cupcake tin. Use a second cutter or glass to cut circles the size of the top of the muffin tin - these will be different sizes if your tin has flared edges. Set aside.
Roll the marzipan between 2 sheets of parchment paper to form a large rectangle. I like to briefly freeze the rolled marzipan with the 2 sheets attached on a baking sheet to firm itup for easier handling. Once chilled, about 5-10 minutes in the freezer, carefully peel off one side of parchment to loosen. Place the parchment back on top and flip over. Carefully peel off the second sheet. This should leave you with marzipan on top of a single sheet of parchment. Use a knife to cut long strips the thickness of the depth of the muffin tin. Carefully lift the strip and place them into the tins, pressing the marzipan against the side of the mold. Any tears can be patched by pressing more marzipan on top. Trim excess and gently push the edges of the marzipan in at the base. I have also had success just pressing room temperature marzipan over the inside of the tin, skipping the rolling and freezing. The result won't be as even but will look the same once unmolded.
Press the small piece of sponge into the bottom of the lined tin (it won't reach quite all the way to the bottom, which is ok as it will leave a small space to be covered in chocolate). Fill with the ricotta mixture leaving a bit of space for the larger sponge. Finally, top with the larger sponge and press down to help it adhere. Transfer to the freezer and freeze until completely set, at least 2 hours.
Gently tap the cakes out (or press out if using silicon molds).
Melt the white chocolate for decorating (I like to place a ziplock bag of the chocolate into a bowl full of hot water. The heat will melt the chocolate and then it will already be in a piping bag - just make sure to dry the exterior well before piping as water can cause the chocolate to seize).
Pipe whatever decorations you like onto the sides of the cakes and then on top of the exposed sponge to from a base for the candied fruit to sit on.
Place candied fruit on top and then let stand for 30 minutes to 1 hour for the cakes to thaw before serving.