Using a mixer, combine 3 cups flour, butter, sugar, and baking powder.
In a separate bowl, whisk 3/4 cup cream, eggs, zest, lemon juice, and vanilla. Pour into flour mixture and mix until well combined.
Use remaining flour to dust work surface and shape dough into a thick flat-topped disk. Cut into 8 even wedges and place on a parchment paper-lined baking sheet.
Stir remaining cream and elderflower liqueur in a small bowl and brush over scones. Bake at 375° for 20-25 minutes until golden brown.
While they bake make the icing by whisking confectioner’s sugar, heavy cream, and elderflower liqueur. When scones come out of the oven, ice them, garnish with extra lemon zest if you like, and serve warm.