Cut an end off the watermelon and cut the rind off. Trim the watermelon into a round cake shape and place on serving platter. Cut a 1/2-inch slice off and use a star cookie cutter to cut 5 watermelon stars and set aside. Place 4 strips of wax paper under the watermelon to protect the serving platter.

In a mixing bowl, add butter and cream cheese and mix to combine. Add remaining ingredients and beat well for a bout 3 minutes. Add more half and half if needed until desired spreading consistency.

Frost watermelon and place remaining frosting in a piping bag with a star tip and decorate as you like.

To decorate the cake - slice strawberries into 3-4 slices and place around bottom of cake and use blueberries and raspberries to decorate. Remove wax paper and place in refrigerator until serving.

Thread blueberries onto wooden skewers and gently skewer watermelon stars and place in refrigerator until needed. Place on top of the cake before serving.