Place Strawberries in food processor; purée until smooth.

Transfer strawberry purée to a saucepan over medium heat; bring to a boil, stirring often until purée is reduced by at least half, about 20 minutes; let cool.

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

Beat in 1 cup of sugar just until blended.

Beat vanilla extract and 2 tablespoons of strawberry purée in to butter and sugar just until blended.

Repeat with 1 cup of sugar followed by 2 tablespoons of strawberry purée two more times

Done! You may want to add more strawberries to add a stronger strawberry taste or more sugar to sweeten it more.