If Using Fresh or Frozen Strawberries

Make the Puree:

• Add the strawberries to a food processor or blender and puree until smooth. Note: If using frozen, you need to thaw before. You will get about 1 1/4 cup.
• Add the strawberry puree to a saucepan or skillet. Cook over medium heat, stirring constantly until mixture begins to thicken and bubble, about 5 to 10 minutes.
• Reduce the heat to medium-low and allow the strawberry mixture to simmer for 15 -20 minutes until reduced to half; about 1/2 cup or so. Remove from heat, pour into a bowl, and set aside to cool.

  Note: You can make the strawberry puree up to 3 days in advance and keep it in the fridge until ready to use.

Make the Frosting:

• Using an electric hand mixer or a stand mixer on medium speed, beat the butter in a large bowl until smooth and creamy, 3 to 4 minutes.
• Reduce the mixer speed to low, add 1 cup of the confectioners’ sugar, and keep mixing until incorporated. Add the milk, vanilla extract, and salt. Once incorporated, add the remaining 3 cups confectioners’ sugar; beat on low speed for 1 minute, then increase the speed to medium-high and beat for 4 to 5 minutes until the frosting is smooth, fluffy, and spreadable, scraping down the bowl once or twice.
• Add 1/4 cup (60 ml) of the cooled strawberry puree, or 1 cup (16 g) freeze-dried strawberries, or 1/2 cup strawberry jam, or 2 teaspoons strawberry emulsion; and mix until well incorporated, about 1 more minutes.
• Before using it on your cake or cupcakes, give your buttercream a last mix by hand with a rubber spatula or a wooden spoon. Be sure to push the frosting against the side of the bowl to push out all of that trapped air and air pockets.