Preheat oven to 350°F. Line cupcake pan with baking cups.
Combine flour, baking soda and salt in a bowl and set aside.
In a large bowl microwave chocolate and butter until butter is melted, 1 to 2 minutes. Stir until well blended. Add sugar and beat until blended. Add eggs, mixing after each addition. Mix in vanilla. Add half of flour mixture to chocolate mixture and mix well. Mix in the buttermilk and then add remaining flour. Mix until just combined.
Fill baking cups with batter.
Bake for 25 minutes or until toothpick inserted comes out clean. Cool for 10 minutes in pan. Move cupcakes to wire rack to cool completely before frosting.
Whisk egg yolks, cream and vanilla in large saucepan until well combined. Add sugar, salt and butter. Cook on medium, stirring constantly for 10 minutes or until thick. Remove from heat and mix in coconut and nuts. Cool for 10 minutes and frost cupcakes.