Mocha Cupcakes:

Let 8 tbsp of unsalted butter, 2 large eggs, and 1/4 cup of sour cream come to room temperature.

Place an oven rack in the middle position, and preheat your oven to 350 F (175 C). Prepare a muffin pan with cupcake liners. This recipe will make 12 cupcakes.

In a medium-sized mixing bowl, add in 1 1/2 cups cake flour, 2 tsp espresso powder, 1 1/2 tsp baking powder, 1/4 tsp baking soda, and 1/4 tsp of table salt. Whisk these dry ingredients together till they're well combined.

In the bowl of your stand mixer, add in the 8 tbsp of room temperature unsalted butter, and beat on medium-high speed for 1 minute till the butter is smooth and creamy. Stop the mixer and add in 3/4 cup of granulated sugar, then continue beating on medium-high for 2 minutes until, until the sugar and butter mixture looks fluffy.

While continuing to beat on medium-high, add in the 2 room temperature eggs, 1 egg at a time, waiting for the previous egg to be fully combined before adding the next one. When the eggs are combined, add in the 1/4 cup of room temperature sour cream and 1/2 cup of strong hot-brewed coffee, just until combined. Stop the mixer and scrape down the bowl as needed.

Turn on to medium-low speed, and slowly add in the dry ingredients mixture, and continue beating just until combined. Stop the mixer and scrape down the bowl as needed to make sure everything is combined. Then mix again on medium speed for another 30 seconds to ensure all the dry ingredients are mixed in and the batter is uniform.

Scoop the batter into the cupcake liners, making sure to only fill them 2/3 of the way up. The batter will rise quite a bit, and going above the 2/3 of the way will result in the batter overflowing.

Bake these cupcakes in the preheated oven at 350 F (175 C) for 15 to 18 minutes, or until a toothpick inserted in the center comes out clean. Let the cupcakes cool in the molds completely to room temperature before frosting them.

Mocha Swiss Meringue Buttercream:

Take 1 cup of unsalted butter (2 sticks), cut it into 1-inch cubes, and let it come to room temperature.

In a large heat-proof bowl like glass or stainless steel, add in 3 egg whites, 3/4 cup of sugar, and 1/2 tsp of salt. Whisk together until they are combined.

Set up a double boiler and heat the egg white mixture in a low heat water bath while continuing to whisk, till the sugar is dissolved (when it feels sticky to touch, and you hardly feel the grains of sugar anymore). If you have a thermometer, it needs to reach 160 degrees Fahrenheit.

Take it off the water bath. Using an electric mixer, beat this mixture until glossy and stiff peaks form. Let it cool down completely to room temperature.

When it is back to room temperature, continue beating and slowly add the 1 cup pre-cut room temperature unsalted butter one cube at a time. The mixture might start looking curdled, but do not worry, and continue mixing until it looks smooth.

When the butter is fully mixed in, add 2 tsp of vanilla extract and 2 tsp of instant espresso powder.

Mix this in until it's smooth. Scrape down the bowl for any unmixed buttercream at the bottom and sides. Then mix on medium speed for a final minute to make sure the frosting is uniform. Leave this in the fridge until you're ready to use it.

Caramel Drizzle:

In a medium saucepan over medium-high heat, add 1/2 cup sugar and 4 tsp water. Do not stir the sugar. Just gently swirl the pan to make sure sugar is heating evenly.

Bring the sugar-water mixture to a boil until it turns into a copper/amber color. Be careful not let it get too dark, otherwise it will have a slightly bitter burnt flavor. Turn off the heat as soon as it turns light amber. It will continue to darken with residual heat.

Then while vigorously whisking, very slowly add in 1/3 cup of room temperature heavy cream, and vigorously whisk it in. Be careful of the hot steam from the initial addition of heavy cream. Adding the heavy cream very slowly will prevent the caramel from seizing up. But if the sugar does seize up into a solid ball, don't worry. Just keep whisking and it will melt again.

Add 2 tablespoons of butter and 1/4 teaspoon of salt, and turn on the heat to medium-low. Mix in the butter and continue whisking for 3 minutes.

Let it cool between lukewarm and room temperature - about 30 to 40 minutes.

Assembling the Cupcakes:

Transfer the lukewarm caramel into a Ziploc bag. Seal the bag Cut a small hole in one of the corners. Pipe caramel onto each cupcake so that the top surface is covered in caramel. Set the leftover caramel aside at room temperature.

Attach a #4B tip to a piping bag, and transfer the mocha swiss meringue buttercream into the piping bag. Frost the top of each cupcake with whatever pattern you like. I like to create a spiral pattern while squeezing the bag. Then I stop squeezing and lift the tip. Do this with all 12 cupcakes.

When all the cupcakes are frosted, I like to finish it off by drizzling the leftover caramel over the frosting in a zig-zag pattern using the same zip-lock bag containing caramel. Store in the fridge if you're not serving them the same day. Allow the cupcakes to come to room temperature (about 2 to 3 hours at room temp) for the frosting to soften before eating. Enjoy!