I got this recipe from a dear friend many years ago and it is a family favorite. With only one of my three kids at home, I don't do as much baking as I used to but when I do make this, my two oldest make sure that they are around to help eat it!
In large bowl of mixer, combine 1 cup flour, sugar, salt and dry yeast. In saucepan, combine sour cream, water and butter. Heat over low heat until liquids are very warm (120-130 degrees). Use your candy thermometer to check the temperature. Gradually add to dry ingredients and beat 2 minutes, scraping bowl occasionally. Add eggs and 1/2 cup flour. Beat at high speed for 2 minutes, scraping bowl occasionally. Stir in enough of the remaining flour by hand to make a soft dough. Turn out onto lightly floured board and knead a few times to form a ball. Cover and let stand 10 minutes.
Divide dough in half. Roll each half into a 14x12 rectangle. Spread 1/2 can of the poppy seed filling on each half. Roll each up from the short side in jelly roll fashion. Pinch edges shut to seal. Place on greased baking sheet, sealed edges down. Cover and let rise in warm place, about 1 hour.
Preheat oven to 350 and bake 35 minutes or until lightly brown. Remove from baking sheet and cool on wire rack. This will also freeze well wrapped in plastic wrap and then wrapped in foil. Thaw at room temperature.