Get out your eggs and buttermilk to bring to room temperature 30 minutes before you begin.
Preheat your oven to 350F degrees and line your cupcake pan with liners.
Zest the 2 limes into a small prep bowl and pour the sugar over it. Using the back of a rubber spatula, press the sugar into the lime zest until the sugar has become fluffy and fragrant. This process should take 2-3 minutes.
In a medium prep bowl, whisk together the flour, baking soda, baking powder and salt.
In the bowl of your stand mixer fitted with the paddle attachment, beat the cold, cubed butter on high until smooth.
Add the lime sugar and beat until incorporated, about 1-2 minutes. NOTE: The butter and sugar will not become light and fluffy because of the oils in the lime.
One at a time, add the eggs and mix on medium-high for 30 seconds after each addition making sure to scrape the sides and the bottom of the bowl to ensure everything is incorporated.
Add the lime juice and mix in. NOTE: The mixture will look curdled, but don’t worry… this is normal.
Using a toothpick, add a small dollop of the gel coloring and mix until the color is uniform. Scape the bowl down to make sure all the batter has been dyed.
In three parts, add the flour with the mixer on low speed. Between each addition of flour, add half the buttermilk. After the last amount of flour has been added, turn the mixer off and scrape the sides and bottom of the bowl and fold in the remaining flour. Turn the mixer back on to medium-high speed for 10 seconds. DO NOT OVERMIX!
Fill cupcake liners 2/3 full with batter.
Bake for 18-20 minutes or until a toothpick comes out clean.
Cool cupcakes in pan for at least 5 minutes before removing to a wire rack to cool completely.
Rum Raspberry Filling
While the cupcakes are cooling, prepare the raspberry rum filling.
In a medium frying pan, stir together the raspberries, sugar, rum, Chambord (optional) and salt over medium high heat.
Cook until the berries break down completely and the mixture begins to bubble, stirring constantly.
Reduce heat to medium and continue to cook until the mixture has reduced by about 1/3-1/2 and has become thicker. Stir constantly during this process.
Pour mixture into a glass bowl and set aside to cool. To speed up the cooling process, place the bowl in the refrigerator.
Whipped Mint Buttercream
In the bowl of your stand mixer fitted with the paddle attachment, cream together the butter and shortening.
Add the powdered sugar mix on medium for about 30 seconds. Add half the heavy cream and beat on medium high until smooth.
Scrape the sides and bottom of the bowl and then mix in the mint extract and salt.
Add the remaining heavy cream and beat on high for 3-4 minutes until smooth and fluffy.
Core the center of each cupcake using and apple corer.
Fill the hole with raspberry filling, pressing the filling down to the bottom of the cupcake. Fill the hole with enough filling so that it is flush with the top of the cupcake.
Fill a piping bag fitted with a round piping tip with the buttercream.