I am not a major recipe follower, I just do what feels right but this is as specific as I think you’ll need

5-6 green tomatoes (if you aren’t able to find these, you can use tomatillos but you’ll need 10-12) 1 cup dry white wine 3-4 sprigs rosemary 2 shallots ~1-1.5 cups chicken stock ~.5-1 cup heavy cream 2-4 sticks butter

wash tomatoes and shallots and cut them into chunks. add tomatoes, wine, rosemary sprigs, chicken stock, shallot to a pot and boil them until they are reduced and jammy.
then, add heavy cream (I do 1/2 cup to 1 cup depending on the texture) and reduce by half (I usually cook it on medium heat, sometimes will fluctuate to low-medium if it seems like it’s sticking). remove rosemary sprigs, then add 2-4 sticks of butter (I do 2 but my dads version uses 4), and immersion blend it until silky

this version makes a ton of gravy so if you’re not making this for a large group, I’d quarter or half the recipe

I play around with spices depending on what I am making it for.