In a quart-size glass jar, combine the oats, buckwheat, spelt, cocoa powder and peanut butter powder and mix together thoroughly. Add the yoghourt whey and enough slightly warm water to wet the dry ingredients well; a quart jar will be perhaps two-thirds full. Set aside and let it all soak for at least 24 hours at room temperature.
When the premix has had its thorough soaking period, empty the jar into a saucepan. Mix in the dry egg solids add just enough water to ensure liquidity (bearing in mind you need to add more water to the dry milk powder and that the final result quantity shouldn't go over 8 cups) and cook over very low heat, stirring quite frequently to avoid any sticking or burning; a very low gas flame is best. Bring it slowly just to a boil and simmer, stirring almost continuously, until the cereals and egg form a thick gruel. It wants to cook maybe ten or fifteen minutes.
Remove from the heat and let it cool a bit. While it's cooling, put the dry milk powder into the VitaMix with a couple cups of water and blend; let it stand awhile for the reconstituted milk to blend. Add the coconut oil and the olive oil to the cooked gruel and stir them in well. Then add the other dry ingredients, the molasses and the syrup. Cut up the banana without peeling it and toss it into the VitaMix with the milk, and liquify the banana. Finally, add the dark brown gruel mixture to the milk/banana mix and process (with the lid on!) on high -- be careful, blending the thick stuff in is a challenge even for the powerful VitaMix and if you aren't careful it may engage its automatic protective cutout, in which case you'll have a long wait on hands before you can finish the job.
The resulting soylent will be THICK, thicker than a milkshake, more like the Dairy Queen frozen-yoghourt Blizzard used to be before they quit selling it. You can consume it on the spot, or put it in the freezer! I do the latter and partially thaw it in the microwave as needed -- but I don't live on soylent. For me at the moment it's still an adjunct to a regular healthy-foods diet, something I use when I'm too tired to prepare a meal, or I take in the truck when I've got a long afternoon of driving ahead of me. You'll need a soup spoon to eat this stuff.
The flavour is indescribable. Neither the molasses nor the peanut butter nor the banana nor the cocoa predominate, in fact they are hard to identify as individual flavours. It's intriguing and indefinite -- qualities which I think will keep my soylent from becoming boring over the long haul. If I'm wrong, well, it'll be dead simple to change the recipe enough to have a totally different taste -- by adding some vanilla pudding mix and axing the blackstrap and cocoa, for instance.
Remember we are dealing with food ingredients here and this is a recipe not a formula, so it can be altered on a whim or for taste reasons. It's permanently subject to change without notice! For the same reason, it doesn't need to be perfectly balanced -- if, as I do, you sometimes fancy a superfood, by all means toss in a couple tablespoons of hempseed, or chia, or moringa, or whatever your food fad of the moment might be! Dietary diversity is good not evil, we are evolved to eat a diverse diet and our ancestors' food choices were far more diverse than our own are today.
I'm sure considerable discussion may ensue here, but there are the basics anyway. I should note that I chose those particular ingredients because I had all of them on hand already and wanted to use them rather than spending a lot of money to build a special soylent from scratch -- I'm pretty well broke at the moment, so I had to use the resources I have on hand. If the result looks strange -- well, so what? It's my PERSONAL soylent and no one else's.