Step 1

Process the raspberries in a food processor or blender until pureed.

Step 2

Place a metal sieve over a bowl and push the puree through a metal sieve to remove the seeds.

Step 3

Add the seedless raspberry puree to a small-medium sized saucepan over low-medium heat and gently boil the mixture while stirring occasionally.

Step 4

Allow to boil for 10-20 minutes, or until it is about 1/4 to 1/3 of the original volume. It should be thick like jam.

Step 5

Remove from the heat, spoon the mixture into a glass bowl, and cool the mixture fully. You can speed up the process by placing the mixture in the fridge or freezer - just be careful of condensation forming and getting into the reduced puree.

Step 6

In a large bowl, beat the butter until fluffy. Turn the mixer on low beat in 2 1/2 cups of the powdered sugar.

Step 7

Then beat in 2-3 tablespoons of the chilled, thickened raspberry puree & salt. (The puree must be fully cooled when you add it - otherwise, the frosting can separate).

Step 8

Beat in the rest of the powdered sugar about 1/2 cup at a time until you get the desired sweetness level. Finally, beat in the whipping cream (if needed).