In a medium-sized mixing bowl or bowl of a stand mixer, mix together cake flour, baking powder, baking soda, and salt.
Add the sugar and brown sugar and mix until well combined.
Add butter and mix on medium-low speed for three minutes. Because there is so little butter, you'll end up with a very fine crumb texture.
In a small mixing bowl, whisk together eggs, sour cream, oil, and vanilla extract until smooth.
Add the egg mixture to the flour mixture and beat on medium speed until just combined.
Dissolve instant coffee into hot brewed coffee to make the coffee super crazy strong.
Slowly add hot coffee to the batter and mix on low speed until just combined. The batter will be liquid. (Don't worry, you didn't do anything wrong. It's supposed to be that way.)
Fill cupcake liners 3/4 full.
Bake for 14 minutes and then test to see if they are done. They are done when a toothpick comes out without wet batter stuck to it. If they are not done, test again in two minutes. If they are still not done, test again in another two minutes.
When the cupcakes are done, remove them immediately from the tins and leave them on a cooling rack (or just on your counter if you don't own a cooling rack) to cool.
Meringue Frosting Instructions
Combine the ingredients in the metal mixing bowl of your stand mixer and set over a pot filled with boiling water on a range, creating a double boiler.
Whisk by hand for a few minutes until the mixture reaches 110 F on a candy thermometer.
Place the bowl on a stand mixer fitted with the whisk attachment. Whisk on medium speed for 10 minutes.
Increase to high speed and whisk until stiff glossy peaks form, about 5 to 10 minutes more.
Pipe a swirl of meringue on cooled cupcakes.
Using a culinary torch, toast the meringue.
Store at room temperature until ready to eat.
For best results with the frosting:
Be sure the inside of the bowl is completely dry,
Make sure there are no egg yolks mixed in with the egg whites, and