For Cake, preheat oven to 350°F. Line a baking sheet with parchement paper and grease with nonstick cooking spray.
Sift together the sugar, flours, salt, baking soda and baking powder.
Whisk together the boiling water, fruit flakes, and cocoa powder. Allow to cool for 5 minutes.
Add the oil, vanilla, flavor, buttermilk and eggs to the cocoa mixture
and mix until combined. Fold in dry ingredients until incorporated.
Spread batter evenly in pan with an offset spatula, then rap pan on counter several times to eliminate air bubbles.
Bake until a wooden pick inserted in center of cake comes out clean, ~20 minutes.
Cool in pan on a rack 10 mins, then run a knife around edge of pan.
Invert onto rack and discard parchment and cool completely, 1 hour.
For Filling, beat together the palm shortening and sugar; mixture will be dry.
Pulverize the fruit flakes in a spice grinder until they are a fine powder.
Whisk together the fruit flake powder and sorbet base until thoroughly combined.
Add fruit mixture and color to the shortening mixture. Beat on high speed for 3 minutes until light and fluffy.
Add water to adjust consistency if needed.
To assemble, place a layer of cake on a cardboard tray; frost the top with 1/4 inch filling.
Place the second layer of cake on top; frost the top with 1/4 inch filling.
Place the third ayer of cake on top; frost the top and sides with 1/4 inch filling.
Box and freeze. Store in freezer top side up. Do not store on side. Thaw cake outside of the box.
To serve a single slice, remove cake from package, cut a slice of frozen cake. Thaw at roomtemperature for 20 minutes.
To serve the whole cake, remove cake from package. Thaw in refrigerator
for 3 hours or at room temperature for 1-2 hours. Clean knife between