Step 1: Preheat your oven to 350°F (175°C).
Step 2: In a medium bowl, whisk together the flour, salt, baking powder, and baking soda. Set aside.
Step 3: In a large mixing bowl, beat the room-temperature butter and sugar together until light and fluffy, about 2-3 minutes.
Step 4: Mix in the sifted cocoa powder, then add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.
Step 5: Gradually add the dry ingredients to the wet mixture, mixing until just combined.
Step 6: Fold in the melted and cooled semisweet chocolate until the batter is smooth.
Step 7: Using a cookie scoop, drop rounded tablespoons of dough onto a parchment-lined baking sheet, creating an indentation in the center of each cookie.
Step 8: Bake for 10-12 minutes, until set around the edges but slightly soft in the center.
Step 9: Allow to cool for 5 minutes on the baking sheet before transferring to a cooling rack. Fill each indentation with melted chocolate or ganache once cooled.