In a small bowl, stir together warm milk, 1 teaspoon (4 grams) granulated sugar, and yeast. Let stand until foamy, about 5 minutes.
In the bowl of a stand mixer, whisk together 2 cups (250 grams) flour, salt, lemon zest, and remaining 2 tablespoons plus 2 teaspoons (32 grams) sugar. Add warm milk mixture and eggs; using the paddle attachment, beat at low speed until a smooth dough forms, about 1 minute.
With mixer on low speed, gradually add 1¼ cups (156 grams) flour, beating until a shaggy dough forms; scrape sides of bowl.
Switch to the dough hook attachment. Beat at low speed until dough becomes smooth, elastic, and slightly tacky, about 12 minutes; add up to remaining ¼ cup (31 grams) flour, 1 tablespoon (8 grams) at a time, if dough is too sticky.
Add butter, 1 tablespoon (14 grams) at a time, beating until combined after each addition (7 to 8 minutes total). Beat until a smooth, elastic dough forms, 10 to 12 minutes.
Turn out dough onto a lightly floured surface, and knead 5 to 8 times. Shape dough into a smooth round.
Lightly oil a large bowl. Place dough in bowl, turning to grease top. Cover and let rise in a warm, draft-free place (75°F/24°C) until doubled in size, 45 minutes to 1 hour.
Line 2 rimmed baking sheets with parchment paper.
Lightly punch down dough. Cover and let stand for 5 minutes.
Turn out dough onto a lightly floured surface, and divide into 12 portions (about 69 grams each). Roll each portion into a smooth round.
Working with one at a time, press or roll flat into a 3-inch disk. (Keep remaining dough covered to prevent it from drying out.)
Place at least 2 inches apart on prepared pans. Cover and let rise in a warm, draft-free place (75°F/24°C) until puffed, 25 to 35 minutes.
Preheat oven to 350°F (180°C).
Place Italian Lemon Pastry Cream in a pastry bag fitted with a ¼-inch round piping tip (Ateco #802). Pipe pastry cream in a spiral on each bun, starting at center and spacing swirls within spiral about ¼ inch apart.
Using a fine-mesh sieve, dust tops with confectioners’ sugar; sprinkle with pearl sugar.
Bake until golden brown and an instant-read thermometer inserted in center registers at least 190°F (88°C), 20 to 25 minutes. Let cool on pans for 10 minutes. Remove from pans, and serve warm, or let cool completely on wire rack.
