1 box red velvet cake mix
2 large eggs
1/2 c. (1 stick) butter
1 tsp. pure vanilla extract
1/4 tsp. kosher salt
1 gal. vanilla ice cream, softened
Preheat oven to 350° and line a large rimmed baking sheet with parchment paper. In a large bowl, combine cake mix, eggs, butter, vanilla, and salt. Mix until evenly combined (The mixture will be very thick.). Spread the batter into the prepared baking sheet and bake until set, 18 to 20 minutes.
Let cool in pan completely, then cut the sheet cake in half crosswise to make two large rectangles. Spread vanilla ice cream onto one half, then place the second half on top to form one large ice cream sandwich. Freeze until the ice cream is firm, about 2 hours, then slice into squares. Serve immediately.
