In the bowl of a stand mixer fitted with the paddle attachment, beat ¾ cup (90 grams) flour, ½ cup (120 grams) hot water, 2 teaspoons (8 grams) sugar, and yeast at low speed until well combined, about 2 minutes. (Mixture will be thick.) Cover with plastic wrap, and let stand in a warm, draft-free place (75°F/24°C) until puffed, 15 to 25 minutes.

Add buttermilk, 6 tablespoons (84 grams) butter, room temperature egg, salt, vanilla bean paste, baking powder, remaining 3 cups (360 grams) flour, and remaining 3 tablespoons plus 1 teaspoon (40 grams) sugar to yeast mixture. Beat at low speed until well combined; increase mixer speed to medium, and beat for 5 minutes. (Dough will be like a very thick batter.) Cover dough with plastic wrap, and refrigerate for at least 1 hour.

Line baking sheets with parchment paper.

On a lightly floured surface, divide dough in half (about 500 grams each). Roll half of dough into a 10-inch circle. (Keep remaining dough covered to prevent it from drying out.) Using a small offset spatula, spread 1 tablespoon (14 grams) butter onto dough circle. Using a pastry wheel, cut dough into 6 equal triangles. Starting from base of each triangle, roll up dough, pinching pointed end to seal. Place rolls, point side down, on prepared pans, and shape into crescents by bringing ends closer together. Repeat with remaining dough and remaining 1 tablespoon (14 grams) butter. Cover and let rise in a warm, draft-free place (75°F/24°C) until very puffed, 30 to 45 minutes.

Preheat oven to 375°F (190°C).

In a small bowl, whisk together egg and 1 tablespoon (15 grams) water until well combined; brush onto rolls.

Bake until golden brown and an instant-read thermometer inserted in center registers 210°F (99°C), 15 to 18 minutes. Let cool on pan for 10 minutes.

Drizzle Vanilla Glaze onto rolls; best served warm. Store in an airtight container for up to 3 days.