Melt about a heaped dessert spoon's worth of block Stork in a pan. Then mix in plain flour until it goes all lumpy and looks horrid. (Bear with me...!) Let that cook for a minute or so.
Then add a small bit of the Oatly cream and mix in thoroughly. Keep adding the Oatly cream a but at a time, whisking constantly so that each time you add a bit more, it is well mixed in before you add the next bit. (I don't use a whisk, I use a fork, I find you get less lumps and a smoother sauce! 
).
When it looks about the right consistency of white sauce, you can then use it in tons of other recipes.
Dairy & soy free Lasagne becomes a possibility, and dairy & soy free macaroni cheese - for that, once the sauce is at the right thickness, coating the back of a spoon rather than running off it, you can take it off the heat and add some grated soy free cheezly to it. Pour over macaroni, hey presto!
Also, by adding a teaspoon of dill to the pan of plain sauce, you can make it into a lovely sauce for fish pie, or just to go over fish.
Would you believe I failed Home Ec?! My teacher would be so proud of me...