This is yummy, although we made a few adjustments the second time around. I ditched the lemon juice. My hubby liked it, but I didn't care for it. I am using vanilla beans. I split it, scrape it and put the seeds in and the pod. However, I remove the pod at the end of the boil. And, I increased the boil time to about 10-15 minutes to let it thicken up just a bit more. 1/2 - 3/4 C syrup per liter of seltzer. Then, for serving time, pour 1-2 ounces of cream or half and half into a glass, add about 6 ounces of soda. Super delicious - cream soda!