Preheat the oven to 400 degrees. Line your muffin tin with cupcake liners and set aside.

For the cupcakes - In the bowl of a stand mixer, combine the flour, sugar, cornstarch, salt, vanilla, baking powder, baking soda, lemon extract or oil (if using), egg and butter.

Use the paddle attachment to mix on low speed until the butter is lumpy and the mixture is crumbly.

Add in the milk and continue to mix until combined. Scrape down the sides and mix again on medium speed for an additional minute. The batter will be thick.

Measure about approximately ¼ of a cup’s worth of batter into each cupcake liner. Each cavity should be about ⅔ full.

Bake in the preheated oven for 16-18 minutes or until golden brown and the center is set. Allow to cool completely before assembling.

For the lemon curd - in a large (8 cup capacity), microwaveable bowl, combine the already melted butter, sugar, eggs, zest and lemon juice. Whisk to combine.

Heat in the microwave for one minute. Stir well. Return to the microwave and heat in one minute increments and stirring well between each interval until the curd thickens. Should take about 5-8 minutes, depending on the microwave. Curd is done when you can stir through it and it leaves a track following your whisk and the curd slowly refills the void.

Strain the curd through a fine-mesh strainer. Discard the zest and any cooked egg pieces, etc.

Cover the bowl with the strained curd with a piece of plastic wrap. Be sure to press the plastic to touch the top of the curd so it does not develop a film. Place in the fridge to chill for approximately one hour or until assembly.

For the meringue - place the egg whites and cream of tartar in the bowl of a stand mixer. Mix on medium speed for about 3 minutes or until soft peaks form.

Add in the salt and about ⅓ of the sugar. Continue to mix on medium speed for about a minute before adding more sugar. Add in small increments and continue to mix for several minutes until stiff peaks form. Scrape the sides and mix again on high for about 10-15 seconds, just to ensure all the sugar gets incorporated. Transfer the meringue to a piping bag fitted with a large star tip.

To assemble - transfer the chilled lemon curd to a piping bag. Do not cut open until ready to fill.

Using an apple corer or a rounded teaspoon, scoop out the center of each cupcake to create a hole in the center. Just about half way down - do not puncture all the way through to the bottom of the cupcake. You can eat or discard the scoop of cupcake.

Cut a small hole in the end of the lemon curd piping bag. Carefully fill each cavity until the brim of the cupcake - do not overfill.

Pipe a large mound of meringue on top of the lemon curd to conceal it.

Use a kitchen torch to quickly toast the meringue, rotating carefully to get all sides. Or, place the decorated cupcakes on a baking sheet and broil in the oven for just a minute or two - just until the meringue begins to brown. Rotate the pan occasionally to get an even toast. This method will heat the entire cupcake, so allow it to cool again before serving or serve warm for a lemon lava-cake experience.