One of my friends who's a local to Vegas insisted that I try Luv It on my visit to Vegas. She was right. I tried it -- twice. Both times, I tried a sundae -- one strawberry and one pineapple. Both times I came away full and happy.
Luv It is beyond unassuming. There's no place there to eat. It's literally a small shop with a window to order from.
Fair warning - they have odd hours (1 PM - 10 PM) and it's just north of the Strip in a less than savory part of Vegas.