LINE a 12-cup muffin pan with paper cups. Stir flour with baking powder and salt. Beat ½ cup butter with granulated sugar and lemon zest, using an electric mixer on medium, in a large bowl, 2 min. Beat in eggs and 2 tbsp elderflower syrup until combined. Gradually beat in half of flour mixture, then half of milk. Repeat additions. Divide between muffin cups.
BAKE in centre of oven until a cake tester inserted in centre of cupcakes comes out clean, 18 to 20 min. Transfer to a rack to cool completely.
FOR icing: Beat 1 cup butter and icing sugar, using an electric mixer on medium, in a large bowl, until light and fluffy. Beat in ¼ cup elderflower syrup and lemon juice.
ICE each cupcake with a spoon or piping bags. Decorate with edible flowers, if desired.
Make it Fancy: Cupcakes
Ingredient Tip: We used Belberry Elderflower Syrup, available on Amazon.ca.