Preheat your oven to 350 degrees (F). Line a baking sheet with parchment paper or a silicone baking mat. Set aside.
In a small saucepan over medium heat add the butter and chocolate chips and stir until fully melted and combined. Remove from heat and allow to cool.
Whisk in the brown sugar, egg, and vanilla until fully combined.
In a medium bowl whisk together the flour, cocoa powder, baking powder, and salt until no lumps remain.
Gently fold the chocolate mixture into the flour mixture until just combined.
Press the dough into the bottom of your prepared baking sheet. It should cover the entire baking sheet.
Place the dough in the preheated oven and bake for 10 minutes. Remove from oven and allow to cool completely.
Once cool, remove the cookie from the baking sheet. Cut the cookie in half. You can freeze the two halves for about 15 minutes to make them easier to work with.
Remove the ice cream from the freezer and allow it to sit out for a few minutes to soften. Stir the ice cream to make sure it is thoroughly softened.
Remove the cookies from the freezer and use a silicone spatula to spread on half of the cookie with ice cream, going all the way to the edges. Place the other half of the cookie on top and gently press down.
Immediately move the cookie to the freezer and allow to freeze for 1 hour to allow the ice cream to firm up.
After the ice cream is frozen, remove the cookie from the freezer and cut the ice cream sandwiches about 2 inches by 3 inches.
Store in the freezer until ready to eat.