- Put oven rack in middle position, but do not preheat oven.
- Generously butter & flour a 10-inch bundt pan or tube pan.
- Sift together sifted flour and salt into a bowl.
- Repeat sifting into another bowl (flour will have been sifted 3 times total).
- Beat together butter and sugar in a large bowl with an electric mixer at medium-high speed until pale and fluffy, about 5 minutes in a stand mixer fitted with paddle attachment or 6 to 8 minutes with a handheld mixer.
- Add eggs 1 at a time, beating well after each addition, then beat in vanilla.
- Reduce speed to low and add half of flour, then all of cream, then remaining flour, mixing well after each addition.
- Scrape down side of bowl, then beat at medium-high speed 5 minutes. Batter will become creamier and satiny.
- Fold in the poppyseeds.
- Spoon batter into pan and rap pan against work surface once or twice to eliminate air bubbles.
- Place pan in (cold) oven and turn oven temperature to 350°F. Bake until golden and a wooden pick or skewer inserted in middle of cake comes out with a few crumbs adhering, 1 to 1 1/4 hours.
- Cool cake in pan on a rack 30 minutes.
- Run a thin knife around inner and outer edges of cake, then invert rack over pan and invert cake onto rack to cool completely.