transition to cow's milk 🐄

I officially breastfed for the first year, despite major medical reasons that prevented my LO to nurse the last month and a half or so. he turned a year April 9th and from then on we have been doing formula and puree (we used to do BLW but the medical reasons really set him back). He is starting to get closer to being able to eat real food again. that said, we are ready to transition to cow's milk and I have no idea where to begin. Do I just stop giving formula and replace it with milk? or do I do half and half?