Grease & parchment line your 4-6" cake pans & preheat the oven to 350°
Prepare the cake recipe & buttercream as per the instructions on those blog posts
While the cakes are baking, prepare the raspberry puree for the raspberry fluff buttercream, unless you are using freeze dried raspberry powder in which case you will just add that at the last stage of mixing your buttercream
For the Compote: It's easier to use frozen raspberries because they break down faster & you don't have to add any liquid for the cooking process, but if you are using fresh berries ~ add a few tablespoons of water to help them cook down.
You can add sugar if you like but since I am adding this to already super sweet buttercream, I am using only the raspberry puree
Let the berries cook over a low heat until they breakdown completely stirring often. This should only take about 20 minutes.
Strain the puree through a sieve, discard the seeds & fibers and once the puree is cold add it to the buttercream recipe at the last stage of mixing
Once the cake layers are cooled, assemble the cake with the raspberry fluff buttercream filling & icing & decorate as you like