Instructions

1. For the Pastry Cream:
2. Bring the milk to a boil in a small saucepan.
3. Meanwhile, in a medium heavy-bottomed saucepan, whisk the egg yolks together with the sugar and cornstarch until thick and well blended.
4. Still whisking, drizzle in about 1/4 cup of the hot cereal milk– this will temper, or warm, the yolks so they won’t curdle.
5. Whisking all the while, slowly pour in the remainder of the milk.
6. Put the pan over medium heat and, whisking vigorously, constantly and thoroughly (making sure to get the edges of the pot), bring the mixture to a boil.
7. Keep at a boil, still whisking, for 1 to 2 minutes, then remove the pan from the heat.
8. Let sit for 5 minutes, then whisk in the bits of butter, lemon juice powder, and lemon zest stirring until they are full incorporated and the pastry cream is smooth and silky.
9. Fold in the poppyseeds.
10. Scrape the pastry cream into a bowl.
11. You can press a piece of plastic wrap against the surface of the cream to create an airtight seal and refrigerate the pastry cream until cold or, if you want to cool it quickly–as I always do–put the bowl into a larger bowl filled with ice cubes and cold water, and stir the pastry cream occasionally until it is thoroughly chilled, about 20 minutes.
12. Using a stand mixer with the paddle attachment add the yeast, warm water, and 1/2 tsp. granulated sugar.
13. Let rest for 5-10 minutes to proof…the batter will puff up. If it does not then your yeast is bad and rolls won’t rise so best to throw out and start again with different yeast.
14. Add in buttermilk, eggs, 1/2 cup granulated sugar, salt, lemon zest, vanilla, and melted butter and mix until fully combined.
15. Add in 2 1/2 cups of the flour and mix until fully combined.
16. Switch to a hook attachment then add another 1 cup flour. Knead mixture until combined.
17.  Continue to knead on low speed about 5 – 6 minutes while adding a little more flour as needed to reach a soft and moist dough (Dough shouldn’t stick to the sides of the bowl but does stick to the bottom).
18. Transfer dough to an oiled bowl, cover with plastic wrap (I find press and seal works best)  and let rise in a warm place until doubled in volume, about 1 1/2 hours.
19. I suggest dividing the mixture up between two greased 9-x-13-inch pans.
20. Punch dough down.
21. Dust a working surface lightly with flour and turn dough out onto surface.
22. Sprinkle top of dough with a little flour then roll dough out into an 20 by 18-inch rectangle.
23. Spread the pastry cream evenly over the dough leaving one inch at the top on one of the long sides.
24. Starting at one of the long sides, roll the dough up, and pinch the seam well to seal.
25. Using a serrated knife, cut the dough into 2 inch thick slices, and then place them in the prepared pans.
26. Cover with plastic wrap and let rise one more time, until doubled in volume, about 1 hour.
27. Preheat the oven to 350F.
28. When the rolls have risen, bake until golden brown, about 25 minutes.
29. Let cool for about 5 minutes. 
30. For the Glaze:
31. Whisk together the ingredients. 
32. Pour over buns. 
33. Sprinkle with extra poppyseeds if desired.