Combine the heavy cream and lavender in a small pot. Heat just to boiling, stirring often, then remove from heat.
Let steep until cooled to room temperature.
Strain out lavender flowers and refrigerate cream for several hours, until completely chilled.
Combine cream, powdered sugar, and vanilla in a mixer fitted with a whisk, and whip for several minutes until soft peaks form. You can alternatively make your whipped cream by hand with a whisk or in a mason jar if you don’t have a mixer.