I'm not sure why people buy $4+ tubs of this at the grocery store. It is heavier than heavy cream and thinner than sour cream. It'll whisk up like heavy cream but will have a much different taste and texture. This is different than making sour cream from scratch.
1.5 c heavy cream
0.5 c low fat buttermilk
Pour ingredients into a clean pint or quart mason jar. Cover and shake the jar a few times. Let sit on kitchen counter for 8 hours; then refrigerate for up to 24 hours.
To use with fresh berries:
Whisk desired amount until it has thickened to stiff peaks. Add 1 tsp granulated sugar and 1/2 tsp vanilla extract. Spoon this over fresh blueberries, raspberries, or strawberries.