Preheat the oven to 350°F. Line a cookie sheet with a silicone baking mat or parchment paper.
In a stand mixer with a paddle attachment (or mixing bowl with an electric mixer) combine butter and brown sugar on medium-high speed until creamed and well combined. Add in the egg and vanilla extract. Beat until completely combined.Pour in instant pudding mix, flour, cacao powder, baking soda, and salt. Mix on low speed until just combined. Stir in chocolate chips.Using a 1½ tbsp cookie scoop, scoop the dough and place on the prepared cookie sheet. Bake 11-13 minutes until the edges are set (don't overbake). Let cool before serving.
Store cookies in an airtight container for up to 4 days.