Preheat the oven to 350°F and line a 12-cup muffin tin with cupcake liners.
In a large mixing bowl, cream the softened butter and sugar together using an electric mixer until light and fluffy, about 2 minutes.
Add the eggs one at a time, mixing well after each addition, then stir in the vanilla extract until fully combined.
In a separate bowl, whisk together the flour, baking powder, and salt. Gradually add the dry ingredients to the wet mixture, alternating with the milk, and mix until just combined. Fold in the finely chopped chocolate chips.
Divide the batter evenly among the prepared cupcake liners, filling each about 2/3 full. Bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean. Let the cupcakes cool completely on a wire rack.
Once cooled, spread a layer of orange frosting evenly over the top of each cupcake using a butter knife or offset spatula.
Place two candy eyeballs on each cupcake to create a Halloween-themed design. Use the black decorating gel to draw spider legs or other spooky details around the eyeballs.