For the Chocolate Bacon Cupcakes
Preheat oven to 350° Fahrenheit.

Cook the bacon until crispy. Chop the bacon into very small pieces and set aside.

Place chocolate and butter in a metal bowl and put the bowl over a saucepan of simmering water. Stir until everything is melted.

Remove the bowl from the water and stir in the sugar. Let the mixture cool for 10 minutes.

Meanwhile, whisk together the flour, cocoa powder, baking powder and salt; set aside.

When the chocolate mixture is cool, beat with an electric mixer or your stand mixer for 3 minutes. The mixture will get just a tad thicker.

Add the eggs one at a time, beating for 30 seconds between each one. After two or three eggs, the mixture will start to get thicker and shinier.

Once all the eggs are incorporated, add the dry ingredients. Mix on a low speed until the dry ingredients are just incorporated.

Add the bacon and fold it in with a spatula.

Scoop the batter into cupcake cups until 1/2 to 2/3 full.

Bake at 350° Fahrenheit for 20-25 minutes, until a toothpick inserted in the middle comes out clean. Let cool for a few minutes in the pan before removing to a cooling rack.

For the Caramel Swiss Meringue Buttercream
Make the caramel
Place half of the sugar and the water in a medium saucepan over medium-high heat. Stir until the sugar is dissolved and the mixture is clear. Let the syrup come to a boil, washing down the sides with a wet pastry brush if necessary to prevent crystals from forming.
Boil the syrup, swirling occasionally, until it changes color to dark amber (~340° on a candy thermometer).

Immediately remove from the heat (the sugar will burn if it gets to 350°). Carefully add the cream, standing away from the pan since the mixture will bubble a lot. Stir the caramel until smooth and transfer to a heatproof bowl to cool. (I actually put the bowl into an ice bath, stirring occasionally, to help it cool faster.)

While the caramel cools, place the rest of the sugar, the egg whites and the salt in the metal bowl of a standing mixer. Place the bowl over a pan of boiling water. Whisk continuously until the sugar is dissolved and the mixture reaches 140° Fahrenheit.

Fit the standing mixer with the whisk attachment and put the bowl in place. Beat the mixture on medium-high speed until it is stiff.

Reduce the mixer speed to medium-low and begin adding the butter, a tablespoon or two at a time. Beat until the butter is no longer visible, and add in more, until it is all added. At some point it will look curdled and broken, but just keep on beating and beating until it gets smooth again. This could take a few minutes.

Switch to the paddle attachment and add the caramel and vanilla extract. Beat on low until combined and smooth, 3 to 5 minutes.

At this point you can frost your cupcakes, or you can refrigerate the buttercream for up to 2 days. When you want to use it, take it out of the fridge and bring to room temperature, about an hour. Rebeat in a mixer fitted with the paddle attachment.