Follow these simple steps to create your Gooey Texas Chocolate Sheet Cake Skillet:

1. Preheat Oven: Preheat your oven to 350°F (175°C).
2. Melt Butter: In a saucepan, melt the butter with the water and cocoa powder over medium heat. Stir until well combined and set aside to cool slightly.
3. Mix Dry Ingredients: In a large mixing bowl, combine the flour, sugar, baking soda, and salt. Whisk until well mixed.
4. Combine Wet Ingredients: In another bowl, whisk together the eggs, buttermilk, and vanilla extract. Add the melted cocoa mixture once it has cooled slightly.
5. Combine Mixtures: Pour the wet ingredients into the dry ingredients. Stir until just combined, being careful not to over-mix.
6. Fold in Chocolate Chips: Gently fold in the semi-sweet chocolate chips until evenly distributed.
7. Prepare Skillet: Grease a large oven-safe skillet with butter or non-stick spray.
8. Pour Batter: Pour the batter into the prepared skillet, spreading it evenly.
9. Bake: Place the skillet in the preheated oven and bake for 30-35 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs.
10. Cool: Remove from the oven and let it cool in the skillet for 10-15 minutes before serving.

This simple process will have you enjoying a warm, gooey chocolate cake in no time!