Beat butter and sugar and beat until light and fluffy.

Add lemon zest and eggs, one at a time, beating until well combined.

Add about a third of the flour and beat to combine.

Mix in half of the milk nd beat to combine. Continue adding, alternating between dry and wet and finishing with the dry.

Stir in vanilla and the blueberries.

Scoop batter into cupcake cups about ⅔’s full and bake for about 20-25 minutes or until a cake tester comes out clean.

Keep aside to cool while making the frosting.

Combine egg whites and sugar in the heatproof bowl of a standing mixer set over a pan of simmering water.

Whisk constantly by hand until mixture is warm to the touch and sugar has dissolved.

Attach the bowl to the mixer fitted with the whisk attachment.

Start on low and gradually increasing to medium-high speed, whisk until stiff peaks form.

Continue mixing until the mixture is fluffy and glossy, and completely cool for about 7-10 minutes.

With mixer on medium-low speed, add the butter a little at a time, mixing well after each addition.

Once all butter has been added, whisk in vanilla.

Continue beating for about 3-5 minutes and do keep scraping down the sides of bowl with a flexible spatula,

Once smooth, stop beating and frost cupcakes as desired.