Creating the Gooey Texas Chocolate Sheet Cake Skillet is straightforward. Follow these simple steps to bake your cake:

1. Preheat the Oven: Preheat your oven to 350°F (175°C) and grease a large cast-iron skillet or oven-safe pan.
2. Melt Butter and Cocoa: In a saucepan, combine the butter, water, and cocoa powder. Heat over medium heat until melted and smooth, then remove from heat.
3. Mix Dry Ingredients: In a large mixing bowl, whisk together the flour, sugar, baking soda, and salt until well combined.
4. Combine Mixtures: Pour the melted butter and cocoa mixture into the dry ingredients. Stir until just combined.
5. Add Eggs and Buttermilk: Add the eggs, buttermilk, and vanilla extract to the batter. Mix until smooth and fully incorporated.
6. Fold in Chocolate Chips: If using, gently fold in the semi-sweet chocolate chips for extra chocolatey goodness.
7. Pour Batter into Skillet: Pour the batter into the prepared skillet, smoothing the top with a spatula.
8. Bake: Place the skillet in the preheated oven and bake for 25-30 minutes. The center should be set but still slightly gooey.
9. Make the Frosting: While the cake is baking, melt the butter for the frosting in a saucepan. Stir in the cocoa powder until smooth.
10. Combine Frosting Ingredients: Remove from heat and whisk in the powdered sugar, milk, and vanilla extract until smooth and creamy.
11. Frost the Cake: Once the cake is done baking, let it cool for 10-15 minutes. Spread the frosting generously over the warm cake.
12. Serve: Enjoy your gooey Texas chocolate cake straight from the skillet or transfer to individual plates.