Step 1

Place strawberries in a blender; puree until smooth.

Step 2

Transfer strawberry puree to a saucepan over medium heat; bring to a boil, stirring often, until puree is reduced by at least half, about 20 minutes. Remove from heat and cool completely.

Step 3

Beat butter with an electric mixer in a bowl until light and fluffy.

Step 4

Beat 1 cup confectioners' sugar into butter until just blended.

Step 5

Beat 2 tablespoons strawberry puree and vanilla extract into butter mixture until just blended.

Step 6

Repeat with 1 cup confectioners' sugar, followed by 2 tablespoons strawberry puree two more times.

Step 7

Beat last 1/2 cup confectioners' sugar into mixture until just blended.