Creating the Gooey Texas Chocolate Sheet Cake Skillet is a fun and enjoyable process. Follow these steps to achieve the best results:

1. Preheat the Oven: Preheat your oven to 350°F (175°C) and prepare a large cast-iron skillet by greasing it with butter.
2. Mix Dry Ingredients: In a large mixing bowl, sift together the flour, granulated sugar, cocoa powder, baking soda, and salt.
3. Melt Butter: In a saucepan, melt the unsalted butter over medium heat. Once melted, add the boiling water and stir until combined.
4. Combine Mixtures: Pour the melted butter and water mixture into the dry ingredients. Mix until well combined.
5. Add Milk and Vanilla: Stir in the whole milk and vanilla extract until the batter is smooth.
6. Incorporate Eggs: Add the eggs one at a time, mixing well after each addition to ensure a fluffy texture.
7. Add Chocolate Chips: If desired, fold in the semi-sweet chocolate chips for an extra chocolatey treat.
8. Pour Batter: Pour the batter into the prepared skillet, spreading it evenly.
9. Bake: Place the skillet in the oven and bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean.
10. Cool: Remove the skillet from the oven and let it cool for about 10-15 minutes.

Following these steps will guide you in creating an incredible cake that is gooey and delicious.