In a separate bowl, whisk together the flour and cocoa powder.
2 cup cake flour, 3/4 cup cocoa powder
Add the eggs to the butter mixture one at a time, beating well after each addition.
4 eggs
Slowly blend one third of the flour mixture into the creamed mixture, then half the milk and coconut mixture, another third of the flour, the remaining milk and coconut, and the remaining flour. Be sure to scrape the sides and bottom of the bowl occasionally throughout this process.
Scoop the batter into each liner, filling about 1/2 to 2/3 full.
Bake for 20-22 minutes, or until a toothpick comes out with a few moist crumbs. Remove from the oven. Tilt each cupcake in the muffin pan so it sits at an angle. Cool like that for 10 minutes, then remove them to a cooling rack to finish cooling.
For the filling:
Heat the dulce de leche in the microwave in 20-30 second intervals, mixing after each interval, until it is smooth and slightly thinned.
13.4 ounce dulce de leche
Combine the toasted coconut with the dulce de leche.
3 cup coconut
Fill a piping bag fitted with a wide tip with the caramel and coconut mixture.
Press the tip of the piping bag into the center of each cupcake and pipe about 1 1/2 to 2 tbsp of the mixture into the cake. Be careful not to overfill the cake as it will crack and break the cake.
For the Frosting:
Melt the butter in a heavy 2-quart saucepan.
1 cup unsalted butter
Stir in the salt and brown sugar and heat the mixture to boiling, stirring constantly.
1/2 teaspoon salt, 2 cup brown sugar
Cook over low heat for 2 minutes, until the sugar is totally dissolved. Stir in the milk and return to a boil, stirring constantly.
1/2 cup milk
Remove the pan from the heat and cool to lukewarm (30-40 minutes) stirring occasionally.
Stir in the vanilla, then gradually beat in the powdered sugar using an electric mixer. Adjust consistency with a little more milk or sugar, if necessary. The frosting should be smooth, creamy and thick enough to hold its shape when piped.
2 teaspoon vanilla extract, 4-5 cup powdered sugar
Pipe the frosting onto the cooled cupcakes.
For the topping:
Place the chocolate in a heat proof bowl.
4 ounce dark chocolate
Bring the cream to a simmer, pour over the chocolate and let stand for about a minute. Whisk until smooth.
3 tablespoon heavy cream
Immediately whisk in the butter, just until incorporated.
1 tablespoon unsalted butter
Allow mixture to cool slightly, then drizzle over the top of the cupcakes.
Finish each cupcake with a sprinkle of toasted coconut.