1 teaspoon vanilla extract or 1/2 vanilla bean, scraped
1/4 teaspoon kosher salt
2 cups whipping (35%) cream
Directions
Preheat your oven to 350°F. Grease two 9-inch square baking pans with cooking spray and line with a sling of parchment paper so that it covers the bottom and comes up two facing sides.
For the cake, in a mixing bowl, or a stand mixer fitted with a paddle attachment, beat together the melted butter, sugar, egg, and vanilla on medium-high speed until well combined and a little lighter in color, about one to two minutes. In a separate bowl, sift together the flour, cocoa powder, salt, and baking powder. Add the dry ingredients to the butter mixture and stir just until combined and the batter is smooth.
Divide the batter equally between the two pans and spread it evenly across the entire base of each pan. Bake until the center of the cookies spring back when touched and look slightly dull, eight to ten minutes.
Remove the cookies from the oven and allow them to cool to room temperature before turning them out onto a work surface and peeling away the parchment.
Line one of the 9-inch square baking pans with plastic wrap so that it hangs over the edges and place one of the cookies in the bottom. Transfer this to the freezer to chill while you make the no-churn ice cream.
For the ice cream, whisk together the condensed milk, vanilla, and salt in a large bowl until well combined. In a separate bowl, or a stand mixer fitted with a whisk attachment, whip the cream until stiff peaks form, about two to three minutes. Using a rubber spatula, gently fold one-third of the whipped cream into the condensed milk mixture. Fold in the remaining cream in two additions and set aside.
Retrieve the cookie in its baking pan from the freezer. Pour the ice cream base over the cookie, spreading it into an even layer, and top with the other cookie. Gently fold the plastic wrap over top to cover and place in the freezer for at least six hours but preferably overnight.