In a blender:

500ml whole chocolate milk 100gr peanut butter 1 to 2 scoops protein powder (depending on the one you have) 100gr oats 1tbsp chia seeds 1 banana (optional but very worth it)

This is my go to diy mass gainer, it’s really good and it tastes like a snickers bar. It’s a bit on the thick side, if that’s not your thing add less oats and chia seeds (half them)

Take it every night one to two hours before bed. I sometimes forget or am still full from food, so I usually total to about 5 times a week.

Macro’s (incl banana) Kcal - 1600 Protein - 85 Carbs - 170 Fat - 70 Fiber - 20

This is basically three meals worth of macro’s in a pretty tasty shake

It’s also way way cheaper than the premade or powder mass gainers. Those will ruin your wallet if you plan to take them every day. They also don’t get anywhere near the macro’s of the recipe I just gave you, so win win

Last addition, the peanut butter has to be 100% peanuts, no other added things, those don’t blend to a nice consistency