here is where you (and definitely my mom) may disagree with me: i prefer it made with whole milk so that it is just a little lighter, and just a little easier to eat a big cup of it in one sitting. that being said, making it with half-and-half or even full cream will make, as you have rightfully guessed, a creamier, smoother and richer dessert. my advice is: try it both ways. you know, for science.

1 16oz container (2 cups) full-fat sour cream
2 1/2 cups whole milk, or half-and-half, or full-fat cream or any variation therein
1 cup sugar
1 tsp. vanilla
1 packet of unflavored gelatin (see note)

*note: in the US, the primary brand for unflavored gelatin is Knox and it comes in little boxes containing four packets. In grocery stores, Knox is always in the same general vicinity as the boxes of Jello.