Preheat the oven to 350°F. Line two 9x9 baking dishes with parchment paper, spray with cooking spray, and set aside.
In a medium-sized microwave-safe bowl add the butter, and chocolate chips. Microwave in 15-second intervals, stirring in between until smooth.
Whisk in the sugar until combined. Whisk in the eggs one at a time, mixing in the first one fully before adding the next. Stir in the vanilla.
In a large bowl stir together the flour, cocoa powder, baking powder, and salt. Add the wet mixture to the dry and stir them both together until fully combined with no dry patches.
Add half the batter to each prepared baking dish and bake for 16-18 minutes until a toothpick inserted into the center comes out mostly clean. It is better to slightly underbake, so if there are a couple of crumbs on the toothpick that is perfect.
Let the brownies cool completely in the pans.
You want the ice cream to be softened but not completely melted. Smooth the ice cream on top of one of the brownies while still in the pan.
Take the second brownie out and remove the paper. Place it on top of the ice cream and gently press it down.
Wrap with foil and place in the fridge until frozen solid about 6 hours.
When ready to serve, remove the foil and lift it out using the parchment paper to help. If it is sticking in the pan, run a butter knife along the sides of the pan and the parchment paper to release it.
Take off the paper, and cut into 9 even bars, serve immediately or pop back into the freezer until ready to serve.
Notes
Use any ice cream that you like, see some ideas above.
You can use a boxed mix for these brownies or your favorite brownie recipe.
This can be doubled, make in 2 9x13-inch baking pans.
Mix-ins can be added to your ice cream, see some ideas above.