Preheat the oven to 350°F (180°C) and line a 12-cup muffin tin with muffin cups.
Add the flour, baking powder, vanilla, and salt to a bowl and whisk to combine.
Place the butter and sugar into a large mixing bowl. Mix on high speed with an electric mixer for about three minutes, or until light and fluffy.
Add the eggs one at a time, beating between each addition, until very smooth and light in texture.
Add half of the flour mixture and mix on low speed until combined. Pour in the milk and mix again, then add the remaining flour and whisk it in by hand. Don’t over-mix – a few lumps are fine.
Scoop the batter out into the prepared muffin tin, filling each cup three-quarters full. Bake for 18-20 minutes, or until lightly golden in colour and the cupcakes pass a toothpick test. The cakes will fill the cups but not mound too much (a flat top is easier to decorate).
Cool the muffins for about 10 minutes in the tin before removing to cool fully on a rack.
The cupcakes will keep in an airtight container at room temperature for 3-4 days, and freeze well. If frosted, it’s best to refrigerate (take them out half an hour before serving to soften the icing).
To Decorate
To decorate the cooled cupcakes as pictured, pipe buttercream with a large round tip about 1.25 inches (3 cm) high.
Use a small spatula or dough scraper (or flat side of a butter knife) to smooth the frosting on the sides, then move from the outside in on the top to form a flat top.
Don’t worry if it’s perfect, as the sugar will hide small imperfections. Chill for 10 minutes, then roll the outer edges of the frosting in coarse sugar. Dip the top in the sugar.
Place sprigs of rosemary, upside down, into the frosting.
Notes
* Substitute two teaspoons of vanilla extract. Add to the egg/sugar mixture after beating the second egg in.