Preheat oven to 350 F. Butter two 8 inch baking pans. Line the baking pans with parchment paper making sure that two of the sides have parchment paper extending over the edges. (this will help you lift the brownies once their done baking and freezing)
In a microwave safe bowl, add the butter and chocolate chips. Melt the butter and chocolate stirring every 30 seconds, until melted and smooth. Set aside.
Add flour, unsweetened cocoa powder, baking powder, espresso coffee powder (if using) and a pinch of salt to a medium bowl. Whisk until combined. Set aside.
To a mixer bowl, fitted with a whisk attachment, add eggs, brown sugar and granulated sugar. Whisk until mixture is thick and combined. About 3 minutes.
Add the melted chocolate and butter, whisk on low speed until combined.
Add the milk, whisk until just combined.
Add the flour mixture and whisk until incorporated. The brownie batter will be thick!
Evenly spread the brownie batter between the two prepared baking pans.
Bake for 12-14 minutes or until slightly puffed and toothpick inserted comes out clean.
Cool the brownies completely in the brownie pans. Do not remove them from the pans.
Take out the ice cream, and let it sit on the counter until it’s soft but not melted. While the ice cream is softening, place the brownies with the pans into the freezer to firm up.
Spread ice cream into one of the brownie pans. Remove the second brownie from the pan then peel the parchment paper. Place over the ice cream.
Freeze until firm.
To remove: Lift the ice cream sandwiches using the expended parchment paper. (If needed use a butter knife to loosen the edges) Transfer to a cutting board. Using a sharp knife cut the ice cream sandwiches into rectangles or squares.