It is my experience that plants given too much fertilized garden soils in pots get pale or yellow from the nitrogen fertilizer in the mix burning the roots and stunting growth or outright killing the plant.
I can’t be certain if your mix was a little too rich or not enough without better details to what ratio and what brand of garden soil and potting soils where used.
I recommend only using a balanced Potting Mix in your pots for the futer.
To try and correct the leaf color I would try a liquid fertilizer like Miracle-gro at ½ recipe and apply it to just the leaves of your basil plant and not into the soil.
If the leaves green up some from the first feeding then feed the leaves again one week later with the full liquid food mix recipe, if the leaf color improves even more than I would be sure that I could use the liquid food into the soil in the third week and every week after.

If the leaf is tender and not tough it should have good flavor and can be used for cooking.

The basil plant is a very quick grower. If it is still mostly green in the stems and not woody looking I believe it can come back big and full with proper sun, feeding, and watering. If you feel the recovery is taking a little to long for your needs you can plant a small transplant to take its place to make sure you will have enough for this season.