Preheat the oven to 350°F (175°C) and grease and flour a 9x13-inch baking pan.

In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, baking powder, baking soda, salt, and unsweetened cocoa powder.

Add the whole milk, vegetable oil, large eggs, and vanilla extract to the dry ingredients and mix on medium speed for about 2 minutes until smooth.

Carefully stir in the boiling water until fully combined; the batter will be thin.

Pour the batter into the prepared pan and bake for 30 to 35 minutes, checking for doneness with a toothpick.

Once cooled for 10 minutes, poke holes evenly across the cake surface with a wooden spoon handle.

In a bowl, mix the sweetened condensed milk, shredded coconut, and chopped pecans, then pour over the warm cake.

Allow the cake to cool completely in the pan; refrigerate if in a hurry.

Spread chocolate frosting over the cooled cake and serve.