Add the raspberries to a heavy-bottomed saucepan and place over medium-high heat. Cook over medium heat, stirring occasionally, until the berries break down, about 10 minutes.
Strain through a fine-mesh sieve into a bowl, pressing against the solids; let cool completely.
In a large mixing bowl beat the softened butter for 1 minute.
Beat in the powdered sugar 1 cup at a time, beating after each cup.
Add the salt and raspberry puree and beat for another 2 minutes.
Once all the sugar is incorporated, add the raspberry champagne. Beat on high until light and fluffy, about 3 minutes.