Preheat the oven to 350°F. In a large mixing bowl, whisk together the flour, cocoa powder, and salt. In a separate bowl, combine melted butter and sugar until smooth. Add eggs one at a time, mixing well after each addition. Stir in vanilla extract.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Fold in chocolate chips. Avoid overmixing to maintain a tender texture.

Divide the batter evenly among the cupcake liners, filling each about two-thirds full.

Bake in the preheated oven for 18-22 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs. Let them cool completely on a wire rack before frosting.

In a large bowl, beat the softened butter until creamy. Gradually add the powdered sugar and cocoa powder, mixing until smooth. Add milk as needed to reach the desired consistency. Stir in vanilla extract.

Once the cupcakes are completely cooled, pipe or spread the frosting onto each cupcake. Decorate with chocolate shavings or sprinkles if desired.

Store the frosted cupcakes in an airtight container at room temperature for up to 3 days, or refrigerate for longer freshness.

Unfrosted cupcakes can be frozen for up to 2 months. Thaw at room temperature before frosting and serving.