Preheat the oven to 180 °C / 350 F and line 5 x 6-cup (or 3 x 12-cup) muffin tins with paper liners.
Using an electric mixer, beat the butter and sugar together until light and fluffy (about 3 minutes). Add the eggs, one at a time, ensuring that each is thoroughly mixed in before the next addition. Stir in the vanilla extract, lemon extract, or essence and lemon zest.
Sift together the flour, baking powder, and bicarbonate of soda. Add the flour mixture in 3 parts, alternating with the milk, to the butter and egg mixture. Scrape the sides of the bowl and briefly mix until smooth, making sure you do not overbeat. Scrape down the bowl once more by hand, then fold in the pistachios.
Spoon out the batter with an ice cream scoop, filling each paper liner three-quarters of the way up. Bake for 20 minutes until golden brown and springy to the touch. Leave to cool in the tins.
While the cupcakes are cooling, make the meringue frosting. In a small saucepan, bring the honey to a boil on the stovetop. In the meanwhile, whisk the egg whites with an electric mixer until stiff peaks form.
Add the salt and continue whisking. When the honey bubbles, slowly add it to the egg whites in a thin stream with the mixer running on high. Add the vanilla extract and continue to mix for a further 7–9 minutes until the meringue is holding its peaks and has cooled down.
Scoop the meringue mixture into a piping bag and pipe it onto the cooled cupcakes. If you have a blowtorch, singe the tips of the meringue to create a beautiful effect and toasty flavour.