My relatives made those same rolls and I ate them when I was a kid. They were sweeter dessert-like bread stuffed with the thick layer of poppy seeds like you described. They were called Hungarian Poppy Seed rolls. Every Christmas my elder relatives would make them and they were my among my favorite foods on the planet. In fact at one point I tried to find these Hungarian Poppy Seed rolls at a bakery or the supermarket, to no avail. Stores didn't seem to make them where I lived.
I think I liked them so much because I was getting a slight high from the opiates.