Apologies for the ambiguous description as I can't remember exactly it's called or the exact details. When I think about OLS, I typically think about regressing $y$ on top of the predictors simultaneously.
The other approach that I am alluding to is, IIRC, where you do some kind of partial regression on a subset of the predictors, and then you're left with partial residuals, and then your regress the partial residuals on the remaining predictors. I may be remembering this incorrectly, but I vaguely recall it was something like this.
What is the name of this strategy? I would like to read about it in more detail.