To make the cake, preheat oven to 180°C (350°F). Grease two springform pans (diameter 18 cm).
Combine flour, baking powder, and sugar in a bowl.
Add liquid ingredients and mix well.
Pour into pans and bake for 40 minutes or until an inserted toothpick comes out clean.
Let cool for 10 minutes, remove from pans and transfer to a cake rack.
Let cool completely.
To make the filling, combine all ingredients and mix well.
Set aside.
To make the buttercream, whip the sugar and the coconut oil until light and creamy.
Add agave nectar and raspberry filling and whip until well combined.
To assemble the cake, trim the tops off both cakes to make flat surfaces.
Cut both cakes in half horizontally.
Spread one cake layer with 2-3 tablespoons of filling.
Top with the second layer, spread filling on the layer and repeat.
Put the last layer on top of the cake but don't cover it with filling.
Cover the whole cake in buttercream.
Frost the top of the cake first and then the sides.
Work as precisely as you can so that the buttercream layer is really smooth and even.
Reserve 2-3 tablespoons of buttercream so that you can even out small holes right before you apply the fondant.
Refrigerate the cake over night.
The next day prepare the fondant.
Place half of the powdered sugar in a bowl
In a small saucepan, combine agar, water, and agave syrup. Bring to a boil while stirring constantly.
Stir constantly and simmer for one minute. Remove from heat and add coconut oil.
Stir until oil is melted.
Pour into the powdered sugar and knead until the mixture comes together.
Add more powdered sugar and knead until the fondant is smooth and no longer sticky.
Dust your working surface with cornstarch and roll out the fondant thinly. (I could almost see through mine.)
Lift the fondant over the cake and then start to smooth the fondant out. (See first video above.)
Cut away the excess fondant and wrap it in plastic immediately so it doesn't dry out.
Once you've covered your cake, you can start decorating it.
Have a small bowl with water and a brush ready.
To apply the ruffles, roll out the remaining fondant and cut it into stripes. (Make sure to cover the stripes you aren't working with.)
Start at the top of the cake and glue the fondant stripes to the side of the cake. (See second video.)
If you have any leftovers and small cookie cutters, you can use the leftovers to decorate the top of the cake with small flowers etc.