1. Preheat your oven to 350°F (175°C). If using a homemade pie crust, roll it out and fit it into a 9-inch pie pan. Flute the edges as desired.
2. In a medium bowl, whisk together the sugar, cocoa powder, flour, and salt until well combined. My abuela always said that mixing dry ingredients thoroughly is key for a smooth filling.
3. Add the beaten eggs, milk, vanilla extract, and melted butter to the dry mixture. Stir until the ingredients are fully incorporated and the mixture is smooth.
4. Pour the chocolate filling into the prepared pie crust, spreading it evenly. I find this part almost meditative, reminiscent of the quiet focus my grandmother had when she cooked.
5. Bake in the preheated oven for 45-50 minutes, or until the center is set and the top is slightly puffed. A gentle jiggle in the center is okay, as the pie will continue to set as it cools.
6. Allow the pie to cool completely on a wire rack. This step is crucial for easy slicing and the best texture.
7. Serve with a generous dollop of whipped cream or a scoop of vanilla ice cream, if desired.

From my experience, patience is essential here. Allowing the pie to cool completely is the secret to achieving that perfect slice that holds its shape.