Preheat your oven to 350°F (175°C). Line Mosaic non-stick muffin pan with green paper liners.
In a medium-sized bowl, sift together the flour, cocoa powder, baking powder, baking soda, and salt. Set aside.
Melt the chocolate chips in a microwave, by heating it on 70% power for 1 minute. Repeat if necessary for an additional 30 second, until the chocolate chips are melted. Set aside.
In a large bowl, cream softened butter with granulated and brown sugar together, until creamy and fluffy. Add eggs and mix until they are well incorporated. Stir in the vanilla extract and the melted chocolate. Mix until well combined.
Gradually add the dry ingredients to the wet ingredients, alternating with the milk. Begin and end with the dry ingredients, mixing just until combined. Be careful not to overmix.
Spoon the batter into the cupcake liners, filling each about 2/3 full.
Bake in the preheated oven for about 15–18 minutes, or until a toothpick inserted into the centre comes out clean.
Allow the cupcakes to cool in the muffin pan for a few minutes before transferring them to a wire rack to cool completely.