Gaining

I think cream amount should start incrementally in small steps over a month and more.
I think it needs to be sweetened.
I think berries, peaches, or what you like should be added as if it were yogurt.
I think it should be blended
I think it should be tasty.
I think light cream is heavy enough for starters.

Just my thoughts....as it would be similar for oils.

My wife has about 6-8 tablespoons a day of whipping cream. An extra 400 calories daily..small amount but she drinks a full carton a week. Slow and steady wins the race! In a year she’ll gain around 30-50 lbs based on eating habits and activity. It seems to me that her weight gain from the cream hits all the right spots too but that could just be genetics.

Her weight gain over the years has been up and down. Started around 2007, gain and lose every year or two. Her lowest than was around 160, her highest was 230. Lost weight around 2020 to 170, now back up to 220-225.

Heavy cream is the best

Hmmm, interesting. I could never enjoy plain ole heavy cream from the store, with out considering to use it as a fat source for recipes.
Though the cream in raw milk is delicious.