The actual blessing pronounced by Isaac is recorded in Gen 27:27-29. It is referenced as a single past event in V33, 25, 36, 37.
The solution here is as per some of the standard commentaries:
The Cambridge Commentary simply says:
- blessed] Anticipating Genesis 27:26-29.
Keil and Delitzsch Biblical Commentary on the Old Testament arrives at a similar conclusion
he did not recognise him; and "so he blessed him." In this remark
(Genesis 27:23) the writer gives the result of Jacob's attempt; so
that the blessing is merely mentioned proleptically here, and refers
to the formal blessing described afterwards, and not to the first
greeting and salutation.
Gill is less decisive:
so he blessed him; or intended and determined within himself to bless
him, for the blessing was not given till afterwards; unless this is to
be understood of a common blessing, congratulating him on the quick
dispatch he made, and the great success he met with; and after this
gave him the patriarchal blessing, which as yet he had not, being not
thoroughly satisfied of him, as appears by what follows.