Add the granulated sugar, water, and dried culinary lavender to a small saucepan.

Bring the mixture just to a simmer over medium heat, stirring occasionally until the sugar has dissolved.

Remove from the heat and let the lavender steep for 10 minutes.

Strain the syrup through a fine-mesh strainer to remove the lavender.

Allow the syrup to cool completely before adding it to the buttercream.

Add the softened butter to the bowl of a stand mixer fitted with the paddle attachment, or use a large mixing bowl and hand mixer.

Beat the butter on medium-high speed until light, fluffy, and creamy, about 2–3 minutes.

Gradually add the powdered sugar, mixing on low after each addition until incorporated.

Add the vanilla bean paste and salt and beat on medium-high speed.

Continue beating on medium-high speed and add in the 1 tablespoon cooled lavender syrup and then the 4 tablespoons heavy cream (1 tbsp at a time) until the frosting is light, fluffy, and smooth. About 2-3 minutes. Scrap down the bowl as needed.

Check the consistency. If the buttercream is too thick, add additional heavy cream 1 teaspoon at a time, mixing well between additions, until it reaches your desired consistency.

If desired, add 1 small drop of violet food coloring and mix until evenly incorporated.

Use immediately to frost or pipe onto your favorite cakes, cupcakes, cookies, or other baked desserts.