Preheat oven to 350º. Line 3 (6-cup) muffin pans with desired liners; set aside.
In a medium bowl, sift together flour, baking powder, and salt; set aside.
In a large bowl, combine butter, ¾ cup sugar, and vanilla extract. Using an electric mixer at high speed, beat until smooth and creamy, about 4 minutes.
In a small bowl, combine cream and crème fraîche; whisk until smooth.
Add flour mixture to butter mixture gradually, in 3 parts, alternating with cream mixture, beginning and ending with flour mixture.
In a large bowl and using an electric mixer at medium speed, beat together egg whites and cream of tartar until soft peaks form. Increase mixer speed to high; add remaining sugar, 1 tablespoon at a time. Continue to beat until stiff peaks form. Carefully fold egg whites into batter gradually, in 4 parts.
Divide batter among muffin pan wells. Bake until a wooden pick inserted near the centers comes out clean, 15 to 18 minutes. Let cupcakes cool in pans for 10 minutes; remove to wire racks to let cool completely.
Frost with Royal Icing, using approximately 2 tablespoons per cupcake; garnish with dried lavender sprigs, if desired.
Recipe by Victoria at https://victoriamag.com/lavender-creme-fraiche-cupcakes-recipe/