This raspberry buttercream frosting can be made from fresh or frozen berries. It's thick, creamy, smooth & you can easily pipe it on cakes or cupcakes. You'll love the pretty pink color and fresh raspberry flavor.
Process the raspberries in a food processor or blender until pureed.
Place a metal sieve over a bowl and pour the puree through a metal sieve to remove the seeds. You will need to use the back of a spoon or rubber spatula to push the puree through the sifter. I recommend doing this ½ at a time.
Add the seedless raspberry puree to a small-medium sized saucepan over low-medium heat and gently boil the mixture while stirring occasionally.
Allow to boil for 20-30 minutes, or until it is about ¼ to ⅓ of the original volume. It should be thick like jam.
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.
In a large bowl, beat the butter until fluffy. Turn the mixer on low beat in 2 ½ cups of the powdered sugar. If the powdered sugar is lumpy, be sure to sift it first.
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).
Beat in the rest of the powdered sugar about ½ cup at a time until you get the desired sweetness level. Finally, beat in the whipping cream (if needed).
Notes
Raspberries: If using frozen berries, thawing them in the fridge will make it easier to process in the food processor/blender. You will also need to boil the berries down for longer because there will be more liquid to boil out from the ice. It will likely take closer to 30-40 minutes.
Butter: If using salted butter, omit the salt from the recipe. I personally prefer unsalted butter.
Make-Ahead Tips: Puree the berries, remove the seeds and boil down the puree (steps 1-5) up to 48 hours before you plan to frost the cupcakes. Store in an airtight container in the fridge. Then make the frosting (steps 6-8) the day you plan to frost and serve the cupcakes.
Storage and Make-Ahead Tips: Store frosted cakes & cupcakes at room temperature for up to 8 hours, or in the fridge for up to 3 days. Bring to room temperature on the counter before enjoying. Frosting can be made ahead of time, placed in a container and refrigerated for up to 2 days. Bring to room temperature on the counter, then beat with an electric mixer (if needed) until smooth before frosting cakes and cupcakes.
Makes enough for:
12-18 cupcakes with a piping bag
24 cupcakes with a thin layer of frosting using a knife
9x13 (23x33 cm) inch sheet cake, with some leftover frosting
for a 3-layer 8-inch (20-cm) layer cake, double the recipe
for a 2-layer 8-inch (20-cm) layer cake, multiple by 1.5
for an 8x8 inch (20x20 cm) or 9x9 inch (23x23 cm) pan of brownies or cake, divide the recipe by 2
Nutrition Details: Nutrition information is based off the frosting divided between 18 cupcakes (not including the cupcake) and is an estimate only.