This recipe is made of multiple separate components, to give thorough instructions without making this page super long, I have split each component up into its own recipe to make it easier to read. Click on each component below to be taken to the full recipe and detailed instructions.
Place one of your genoise cake layers into the base of a pastry ring or loose-bottomed cake pan. Do not grease the cake pan.
Find the prettiest strawberries in the box and slice them in half. It's best if you can find ones that are all roughly the same size.
Place the strawberries in a ring around the outside of the cake, with the inside of the strawberry facing the cake ring/pan.
Brush a layer of strawberry simple syrup all over the sponge cake.
Put the creme mousseline into a piping bag and cut a hole in the end - there is no need for a nozzle. Pipe creme mousseline all around the strawberries to fill in all the gaps (see pictures above). Once all the gaps are filled in, pipe a thin layer of creme mousseline in the middle of the cake to cover any cake layer you might still be able to see.
Fill the center of the cake with strawberries, with the tops cut off, standing upright (see pictures), until the whole cake is covered in strawberries.
Pipe more creme mousseline on top of the strawberries to form a thick layer - it should cover the top of the strawberries so they can't be seen anymore. Use a palette knife to smooth it out nice and flat.
Put the second half of the genoise cake on top of the creme mousseline layer and press it down gently.
Brush some more strawberry simple syrup all over the top cake layer.
Put the remainder of the creme mousseline on top of the genoise cake and smooth it out flat. Place Fraisier cake in the fridge to set for at least 4 hours - or even overnight.
Once the fraisier cake has set, remove it from the fridge and let it sit for 5 minutes.
Try to very gently remove the cake from the cake ring/pan. It should slide easily, but if there is any resistance, you can use a hair dryer or blow torch to gently heat the outside of the ring very slightly, then try again.
Once the cake is removed from the cake pan, put it back in the fridge while you prepare the marzipan.
Take a small amount of red food coloring and knead it into the marzipan with your hands (you may want to wear gloves until the color is incorporated evenly. Roll the marzipan out thinly on your worktop, using a little powdered sugar underneath so it doesn't stick.
Use the cake ring or pan that you used for the cake to trace and cut a circle of marzipan the same size as your cake. Then lift it from the worktop and place gently on top of your fraisier cake.