Start by preheating your oven to 350°F. Then line a 12-cup standard muffin pan with cupcake liners to get everything ready.

In a medium mixing bowl, whisk together the flour, baking powder, and salt until well combined. Then just set it aside for now—it'll come in handy soon!

In a large mixing bowl, use an electric hand mixer (or a stand mixer with the paddle attachment) to mix the butter and sugar on low speed until they come together. Then turn up the speed and beat it all until the mixture turns pale and fluffy—this should take about 3 minutes. Don’t forget to scrape down the sides of the bowl so everything gets mixed evenly!

Mix in the egg first, then add the egg yolks and vanilla extract. Give the bowl a good scrape to keep everything mixed evenly.

Next, add 1/3 of the flour mixture and mix on low speed just until it's combined—don’t overmix! Pour in the milk and mix again. Now add another 1/3 of the flour mixture, blend it in, then mix in the buttermilk. Finally, add the last 1/3 of the flour and mix until everything is just combined. Nice and easy!

Grab a rubber spatula and gently scrape down the sides of the bowl, folding the batter to make sure everything is mixed evenly. Now take about half of the dough (around 12 oz) and move it into a separate bowl. Sprinkle in the espresso powder and fold it in until it’s mostly blended—don’t worry if you see some specks, they’ll melt right in as it bakes!

Scoop about 2 tablespoons of the plain vanilla batter into each cupcake liner and gently spread it out to make an even layer. Then add 2 tablespoons of the espresso batter right on top.

Pop the pan into your preheated oven and bake for 18 to 22 minutes—just until a toothpick poked into the center comes out clean.

Let the cupcakes cool in the pan for a few minutes, then transfer them to a wire rack to cool completely. Time to enjoy the delicious smell while they cool!

In a large mixing bowl, use an electric hand mixer to beat together the mascarpone and powdered sugar until smooth and well combined.

Pour in the heavy cream and start whipping on medium-low speed, then gradually crank it up to high. Keep whipping until medium-stiff peaks form. Add the vanilla and whip a little more until the frosting is super thick and holds its shape—hello, very stiff peaks!

Now you’re ready to frost those cupcakes! Pipe or spread the frosting on top, then give them a light dusting of cocoa powder for that fancy touch. Keep the cupcakes stored in the fridge until you're ready to enjoy.