Melt the baking chocolate with water over medium-low heat. Stir constantly. This "blooms" the chocolate, intensifying the cocoa flavor before it even hits the batter.
Beat the butter and sugar for at least 3 minutes until light and airy. Pour in the melted chocolate while mixing.
Spray three 8-inch cake pans with non-stick spray, but then line the bottoms with parchment paper circles. This is vital for German chocolate cake, as the crumb is very tender and can stick easily.
Divide the batter evenly. Bake at 350°F for 35–40 minutes. Cool the cakes completely in the pans before attempting to flip them out.
For the frosting, combine the butter, sugars, and evaporated milk in a saucepan. Whisk in the egg yolks.
Cook over medium heat for 10–12 minutes. You are looking for a bubbly, thick custard. Pro Tip: If the sauce coats the back of a wooden spoon and leaves a clear trail when you run your finger through it, it’s ready.
Stir in the coconut and pecans. Let the frosting cool for at least 30 minutes to firm up.