Gaining

Honestly heavy cream is the best way to go, you could mix it with brownie mix for more carb cal or mix brownie with water if your lactose intolerant.
I usually have a hard time swallowing the same flavour, it makes me sick so with my funnel i stick the tube fown my throat, but this is p extreme and rly only want to try with little to no gag reflex

Try consuming as much of what ever weight gain concoction in 20 minutes. This is because it takes 20 minutes for your body to say your full once you eat enough food.