01 - Combine dried lavender buds and boiling water in a small bowl. Allow to steep for 10 minutes, then strain and cool the infused liquid. Discard the buds.
02 - In a large bowl, beat softened butter with an electric mixer on medium-high speed until pale and creamy, about 3 minutes.
03 - Gradually incorporate powdered sugar, 1 cup at a time, beating on low speed until fully blended after each addition.
04 - Add cooled lavender infusion, vanilla extract, and heavy cream or milk. Beat on medium-high speed until the mixture becomes light and fluffy, about 2 to 3 minutes.
05 - If desired, add a small drop of purple food coloring and blend until a consistent hue is achieved.
06 - Immediately frost completely cooled cakes or cupcakes. Garnish with edible flowers if preferred.