Preheat The Oven & Prep Your Pans Properly

1. Preheat The Oven. Start by preheating the oven to 350 degrees F.
2. Line two 8×8″ metal pans with parchment, leaving an overhang of parchment paper over the sides of the pan that you can use to lift the brownies out later. (See the photos or video as needed for a visual!). Do NOT use glass pans or the brownies will not bake properly.
3. Cut two 8×8″ squares of parchment paper and set these aside. (You’ll use these for the tops of the brownies)

Make The Brownies:

1. Measure The Dry Ingredients. In a medium bowl, combine the flour, cocoa powder, baking powder, and salt. Whisk to combine and set aside. (Weigh your flour and cocoa powder for the most accurate results, or at least use the scoop and level method to measure as accurately as you can.)
2. Melt The Butter & Combine With Sugar. Start the brownies by melting the butter in a large microwave safe bowl (or in a saucepan on the stovetop). Add the sugar to the melted butter and mix until the mixture looks like wet sand.
3. Add Eggs One At A Time, Then Add The Vanilla. Add the eggs to the sugar/butter mixture one at a time, beating 20-30 seconds after each addition. Then, add the vanilla and stir until well combined.
4. Add The Dry Ingredients A Little At A Time, mixing until the batter is fully combined. It’ll be on the thick and sticky side at this point.
5. Divide The Batter Between The Two Pans. Weigh it to get as accurate as possible, or use a measuring cup to divide and scoop the batter as evenly as you can between the two pans.
6. Gently Smooth The Batter. Use an offset spatula or the back of a spoon to gently spread the batter into an even layer. (Again, it’ll be very sticky, so just do your best! Securing the parchment paper to the sides of the pan with chip clips or binder clips while you’re spreading the batter can help. Remember to remove the clips before baking!)
7. Gently Press A Parchment Square Onto The Surface of each pan of brownies. This helps the brownies bake into an even layer and makes it easier to gently spread the batter into an even layer.
8. Bake & Cool. Pop the brownies into the oven and bake 15-16 minutes, or until still soft but no longer gooey. (You don’t want to over-bake the brownies or they’ll be too hard to bite through when frozen.) While the brownies are hot, carefully remove the top square of parchment from each pan of brownies. Cool the brownies for 5 minutes in the pans, then use the parchment overhang to remove ONE of the batches of brownies from the pan. (This will be the top of your ice cream sandwiches.) Transfer the brownies (leaving them on the base layer of parchment so it’s easier to assemble later) to a wire cooling rack and allow the brownies to cool an additional 10-15 minutes, while your ice cream softens.

Assemble The Ice Cream Sandwiches:

1. Add The Ice Cream To The Base Layer. While the brownies are cooling, remove the ice cream from the freezer to soften slightly. Use a butter knife to remove thin sections of ice cream, and place the ice cream on top of the brownie layer that’s still in the pan (the base layer of the ice cream sandwiches). Use gentle pressure with the back of a flexible spatula or an offset spatula to spread the ice cream into an even layer. Be gentle so you don’t smash the base brownie layer!
2. Cover With The Top Layer Of Brownies. Use the parchment lining of the top layer of brownies to help you lift and transfer the top brownie layer. Work quickly to turn the top brownie layer out on top of the ice cream. (Work quickly and carefully, as the brownies are soft!) Use gentle pressure to press the top layer of brownies into the ice cream. (If your brownie breaks, don’t panic. You can patch it together as needed. I promise!) 
3. Freeze Completely. Remove the parchment from the top layer of brownies, and cover the pan with food wrap (plastic wrap, Press ‘n’ Seal, or foil). Then transfer the pan to the freezer. Freeze at LEAST 6 hours, up to 12-18 hours in advance. (Otherwise the ice cream will be too soft when you slice them!)
4. Slice & Serve. When you’re ready to serve the ice cream sandwiches, run a thin knife around the edges of the pan. Then use the parchment handles to remove the ice cream sandwiches from the pan and transfer to a cutting board. (Lifting it out of the pan is the hardest part, but don’t give up!) Use a long, sharp knife (and your muscles!) to slice the brownies into 10-12 rectangles or 9 squares for ice cream sandwiches. 
5. Store Leftovers. Wrap individual ice cream sandwiches in parchment or press n seal, then store in a freezer-safe bag or airtight container in the freezer up to 1 month. Allow frozen ice cream sandwiches to soften 5-10 minutes before eating.