Preheat your oven to 350 degrees. Grease two 9-inch round cake pans with coconut oil or butter. Set aside.

In the bowl of your stand mixer cream together the unsalted butter and granulated sugar. This will take 3-4 minutes and the mixture should be starting to stick to the sides of the bowl when it's ready.

Add the brown sugar, sour cream, pineapple, juice and coconut extract. Blend just until mixed together.

Add the gluten free flour, baking powder and baking soda to the wet ingredients. Mix just until blended together and smooth batter forms. The batter will be thick and sticky.

Pour the batter evenly into the two greased 9-inch cake pans and bake at 350 degrees for 30-35 minutes. The cakes will be golden brown and a toothpick inserted in the center will come out clean when done.

Let the cakes stand in the pans for 10 minutes and then invert onto a cooling rack.

In a saucepan over medium high heat add the can of crushed pineapple and granulated sugar for the filling. Cook at a simmer for 5-6 minutes until most of the juice has evaporated and the mixture has thickened. There will still be a little bit of juice that will be absorbed when the filling cools.

Once the cakes and filling have cooled completely (I like to bake the cakes the day before) you can make the frosting.

In the bowl of your stand mixer add the room temperature butter and beat until it is creamy. Add one cup of sifted powdered sugar and blend until incorporated together. Do this for all four cups of the sifted powdered sugar. Then, add the milk and coconut extract.

I use 1 tablespoon of milk for frosting I want to pipe and 2 tablespoons of milk for frosting I want to spread.

Cut the two cakes in half as evenly as you can to form four round cakes. Place a cake onto your cake stand and top with the pineapple filling. Repeat this step until all four layers are on. Don't put pineapple filling on the very top.

Frost the outside and top of the cake with the coconut buttercream frosting.