Preheat the oven to 350°. Line 4 cups of a muffin tin with paper liners and spray liners with non-stick cooking spray. This will help to prevent them from sticking.
Pour the milk into a small bowl. Add the vinegar and let sit while you prepare the rest of the ingredients.
Sift together the flour, cocoa powder, baking soda, and baking powder in a small bowl.
In another bowl, whisk together the coconut oil, vanilla, and brown sugar. Add the dry ingredients to the coconut oil and brown sugar mixture in two batches, alternating with the milk mixture.
Divide the batter between the 4 muffin cups and bake for 15-18 minutes, or until a toothpick inserted comes out clean. Let cool on a wire rack.
Next, make the frosting: In a small mixing bowl, add the evaporated milk, powdered sugar, cocoa powder, and butter, using an electric mixer blend until smooth. Frost the cupcakes when they have cooled completely.
Top with coconut and chopped pecans.