Preheat your oven to 350°F (175°C). Grease a 9x13 inch baking pan.
In a large mixing bowl, combine the German chocolate cake mix, water, vegetable oil, and eggs. Beat with an electric mixer on medium speed for 2 minutes until well combined.
Pour the batter into the prepared baking pan and spread evenly. Bake for 30 minutes, or until a toothpick inserted into the center comes out clean.
While the cake is baking, prepare the coconut-pecan filling by combining the evaporated milk, granulated sugar, and cocoa powder in a saucepan over medium heat. Stir continuously until the mixture starts to thicken, about 5-7 minutes.
Remove the saucepan from heat and stir in the shredded coconut, chopped pecans, powdered sugar, and vanilla extract. Mix until well combined.
Once the cake is done baking, remove it from the oven and let it cool for about 10 minutes. Using a toothpick or skewer, poke holes all over the top of the cake.
Pour the coconut-pecan filling over the still-warm cake, ensuring it seeps into the holes. Allow the cake to cool completely before serving.
Slice and serve the delicious German Chocolate Poke Cake to your guests!