Oatly oat milk (or Boring oat milk in NZ) is sweet... but it has no added sugars. I believe they are malting and mashing the oats to create sugars from the starches in the oats. Then they can say "no added sugars" and have no sugar listed in the ingredients.

So there are recipes on line that have you blend 1 part rolled oats with 4 parts of water and filter thorugh a "nut mllk bag"' and people add sweeteners. But they still suffer "sliminess" and try to combat it by using ice water and other tricks, but it doesn't work well.

Fuck that. I'm going to try mashing. This is totally untested but this is my rough plan:

Malt (I could just buy diastatic malt, but I'm making my own):

Soak wheat (not oats, I don't have them .. 6 row barley is best but I don't have that either) berries in water until they fully swell, 8 hours.

(I'm using a french press, easy to drain through)

Keep in the dark, but rinse and drain twice a day for about 3 days unil the sprouts are as long as the grains.

Dry them at about 40 C in the fan-bake oven (no higher than 55 C)

Grind them into a fine powder.

Oat milk:

Blend 1 part rolled oats (not whole grain, not quick) with 4 parts water.

Cook at 53-59C to gelatinize, 20 minutes

Bring to boil and boil for 20 minutes.

Cool to 67 C.

Add malt (unknown how much I should add), and maintain at 67 C

Within 30 minutes it should very much sweeten and lose it's sliminess. Stop when it's nice by raising past 77C to denature the enzymes.

Cool, strain and refrigerate.