Place a loaf pan in the freezer, line with parchment paper for easy clean up.
In a large bowl combine the sweetened condensed milk, crushed oreos, vanilla extract, and salt. Use a spatula to mix together until fully combined.
In a medium bowl or in the bowl of a stand mixer fitted with a whisk attachment, beat the heavy whipping cream until stiff peaks form. Be sure not to over whip.
Fold the whipped cream into the condensed milk mixture until no longer streaky
Pour the mixture into the cold pan, place in the freezer and allow it to chill for about 5 hours or until the ice cream is firm enough to scoop.
Line a 1/2 sheet baking pan with parchment paper. Set aside.
Preheat your oven and prepare the brownie batter according to the instructions on the box.
Pour the brownie mixture on the prepared sheet pan and spread into a thin layer. It should cover at least half of the baking sheet.
Bake the brownie batter for 20-25 minutes or until a toothpick inserted in the center comes out clean. You want the brownies to be rather firm, so you may need to bake a little longer than you normally would.
Remove the brownies from the oven and allow to cool completely at room temperature.
Once cooled, cover with foil wrap and transfer the baking sheet to the freezer for about 15 minutes.
Remove the ice cream from the freezer and allow it to soften for 5-10 minutes, just enough to scoop and spread easily, not melt.
Remove the brownies from the freezer and cut the sheet in half. Scoop the ice cream onto one half of the brownie and use a spatula to evenly spread the ice cream over the brownie, going all the way to the edges.
Place the other half on top and gently press down. Return to the freezer for at least 1 hour.
Remove from the freezer and cut the brownies into 12 equal sized sandwiches.
Store in the freezer covered until ready to eat.
Line your loaf pan with parchment for easy clean up .
Be sure not to over whip your whipping cream or it will break down.
Bake the brownie batter for 20-25 minutes or until a toothpick inserted in the center comes out clean.
You want the brownies to be rather firm, so you may need to bake a little longer than you normally would.
When spreading your ice cream, make sure you spread the filling all the way to the edges!
Make sure you use a sharp knife when cutting your squares.