Preheat the oven to 350°F. Line mini muffin tin with paper liners. Whisk together flour, cocoa, sugar, baking soda, baking powder, and salt. With mixer on low speed, add eggs, buttermilk, oil, extract, and the water; beat until smooth and combined.

Spoon the batter into liners about two-thirds full. Bake approximately 15 minutes, or until tester comes out clean. Transfer tins to wire racks and allow to cool for 10 minutes; turn cupcakes onto racks and let cool completely. Cupcakes can be stored overnight at room temperature, or frozen up to 1 month in airtight containers.

To finish, use a paring knife to cut a cone-shaped piece (about 1/2 inch deep) from the center of each cupcake and throw away the pieces (or eat them). Spoon 1 to 2 teaspoons warm Salted Caramel Filling into each hollowed-out cupcake. You will notice the caramel will sink into the cupcake a little, just fill it up a bit more. Sprinkle a pinch of sea salt over filling.

Use a pastry bag with a medium open-star tip and pipe Dark Chocolate Frosting onto each cupcake, swirling tip and releasing as you pull up to form a peak. Garnish each cupcake with a pinch of sea salt. Cupcakes are best eaten the day they are filled and frosted. Store at room temperature in airtight containers - do NOT refrigerate.

Heat sugar with the water and corn syrup in a heavy saucepan over high, stirring occasionally, until syrup is clear; clip a candy thermometer to side of pan and stop stirring.

Cook until syrup comes to a boil, washing down sides of pan with a wet pastry brush as needed. Boil, gently swirling pan occasionally, until mixture is caramelized and just reaches 360°F. Remove from heat and slowly pour in cream; stir with a wooden spoon until smooth. Stir in sea salt.

Use immediately; if caramel begins to harden reheat gently until pourable.

Icing

Use your favorite buttercream frosting tinted with black food coloring.