In a bowl, add pie crust ingredients and use a pastry cutter to cut the shortening in. On a lightly floured surface, roll into a 1" thick disk. Wrap in plastic wrap and refrigerate for 2 hours.
Preheat oven to 350 degrees Fahrenheit.
Remove from the refrigerator and remove plastic wrap. Roll out into a 12" circle to ensure there is plenty to go up the sides of the pie dish and form a ribbon at the top.
Poke bottom of pie crust with fork to prevent air bubbles from forming as it bakes. If you have pie weights or dry beans, line the bottom of the pie with parchment paper or foil and place them inside. This helps prevent bubbling as well. Bake for 10 minutes, remove from the oven, and remove foil/parchment paper and pie weights if used.
While the crust bakes, make the filling by creaming the butter and sugar together in a mixing bowl. Add eggs, evaporated milk, salt, vanilla, and cocoa to the bowl. Blend well and pour into the pie crust.
Place pie into the oven and bake for 50 minutes. It may be slightly jiggly still, it will set after you remove it from the oven and allow it to rest for at least 1 hour. Serve with whipped cream.