In a medium sauce pan, combine 10 oz frozen raspberries and 1/2 cup sugar. Cook stirring occasionally until jam consistency. Remove from heat and strain through sieve, pushing on the back with a spatula to get all of the juice possible. Off the heat, stir in 2 Tbsp lemon juice and 1 Tbsp gelatin. Pour back into saucepan and place over medium heat, whisk until gelatin dissolved and mixture is hot (not boiling). Remove from heat and cool to room temp (transfer to a different bowl to cool faster) and don't let it sit too long once it's at room temp or it will thicken and become difficult to blend.

Once raspberry syrup is at room temp, beat 3 cups heavy cream with 6 Tbsp powderd sugar on high speed 2 minutes or until whipped and fluffy (do not overbeat or it will turn buttery). Reserve 1 1/2 cups of whipped cream and transfer it to a pastry bag fitted with a large star attachement. Refrigerate until ready to use.