For the Cupcakes

1. Preheat the oven to 350°F and line a 12 cup muffin pan with cupcake liners.
2. In a bowl, sift together the flour, cornstarch, baking powder and salt.
3. In the bowl of a stand mixer fitted with the paddle attachment, mix the sugar and eggs until pale and fluffy, 3-5 minutes. Be sure to scrape the edges.
4. Gently pour in the melted butter and vegetable oil and mix until fully combined.
5. Add the flour mixture and the milk in alternating batches. Mix until combined. There should be no lumps.
6. Fill each liner about two-thirds full and bake for 20-23 minutes, or until a toothpick inserted in the center comes out clean.
7. Remove from the pan and let cool completely before frosting.

For the frosting

1. Bring a medium pot with a few inches of water to a boil.
2. Place the sugar, egg whites, cream of tartar, salt, lemon zest and lemon juice in the bowl of a stand mixer and set it over the pot of boiling water, like a double boiler or bain marie.
3. Whisk constantly for 2-3 minutes, or until the sugar has dissolved.
4. Place the bowl back in your stand mixer and whip on medium speed for 5 minutes.
5. Increase the speed to medium-high and whip for another 3-5 minutes. The frosting should be thick, fluffy, white and glossy, like marshmallow cream.

For the candied lemons (optional)

1. Bring the water and sugar to a boil and stir until the sugar is fully dissolved.
2. Add the lemon slices in a thin layer and stir to fully coat.
3. Simmer for 15-20 minutes or until the lemons are pale and translucent.
4. Remove to a wire rack and let dry for a minimum of 24 hours.
5. Coat with excess sugar, if desired.

To assemble

1. Scoop the frosting into a pastry bag fitted with your desired tip. I used a #2D tip in the photos.
2. Pipe tall rosettes on each cupcake and char the edges just a little with a culinary torch. (You can also place the frosted cupcakes on a sheet pan and broil in an oven for 30 seconds.)
3. Stick half of a candied lemon on the side of the charred frosting (optional).
4. Enjoy!