Achieving viscosity when making cocoa spread, without butter or coconut oil, with colza oil, without nuts I've found several recipes to make cocoa spread (meaning without nuts of any kind), but none really satisfy what I'm looking for.
I've tested a combination of

chocolate, usually 50% cocoa
cocoa powder
concentrated milk (sweetened condensed milk)
Colza oil or sunflower oil
a bit of corn starch (might be a bad idea)
a small bit of guar gum

The result was not really what I wanted, so I'm still looking for advice. I still don't have a good idea of the quantities.
It seems that the cocoa spread I like doesn't use coconut oil or butter, it's often colza or sunflower oil, so I'm still curious how they're able to get this viscosity.
In the ingredient of a cocoa spread I like, I've seen there is soy lecithine, which is something I still don't have.
Is there a temperature I should cook this at? Should I stir more?
I would say that the &quot;thicker milk&quot; advice of the other answer is not bad. Instead of using evaporated milk, it might be mich easier to make it with powdered milk.
Beyond that, I wouldn't try to do whatever a commercial producer is doing. Their recipes tend to be very precisely tuned, created with a lot of effort and know-how, and require steps and technologies that are impossible at home. If, for example, they are hydrogenating their oil, or maybe using only done fraction of it, you will never be able to replicate that.