Put the pecans on a baking sheet and bake at 350°F for 8 minutes. Let them cool slightly and then chop roughly. Set aside.
Whisk together the egg yolks and evaporated milk, then pour into a large saucepan and add the butter, brown sugar, salt and vanilla. Heat over medium heat, whisking slowly just to keep the mixture moving.
Heat the mixture until it thickens and begins to boil. Once it starts boiling keep mixing for about 30 seconds, then turn off the heat and add in the coconut and chopped pecans. Mix them in until evenly dispersed.
Let the German chocolate frosting cool completely before using it.
Notes
The frosting will thicken as it cools, making it easy to spread or scoop onto cakes or cupcakes. Make sure you whisk the eggs into the evaporated milk to break them up completely before applying to the heat as any little pieces of unmixed egg may scramble.