From bon appetit magazine:
MAKES 12 SERVINGS
1 ¼-ounce envelope active dry yeast (about 2¼ teaspoons)
⅔ cup whole milk, warmed
3 tablespoons pure maple syrup
2 large eggs, room temperature
¾ teaspoon kosher salt
1 cup whole wheat flour
2¾ cups all-purpose flour, plus more
6 tablespoons unsalted butter, room temperature, cut into 1-inch pieces, plus melted for brushing (about 4 tablespoons)
⅓ cup granulated sugar, plus more
5 dried juniper berries (optional)
⅓ cup demerara sugar, plus more
Whisk yeast, milk, and maple syrup in the bowl of a stand mixer just to combine, then let sit until foamy, about 5 minutes. Whisk in eggs; add salt, whole wheat flour, 2¾ cups all-purpose flour, and 6 Tbsp. butter and mix on low speed with dough hook until a shaggy dough forms. Increase speed to medium and mix until dough comes together into a smooth ball and pulls away from the sides of bowl, 10–12 minutes.
Place dough in a buttered large bowl and cover. Let sit in a warm spot until doubled in size, 1–1½ hours.
Preheat oven to 400°. Butter a 13×9″ baking dish and sprinkle with granulated sugar, tapping out excess. If using juniper berries, finely grind in a spice mill or using a mortar and pestle. Mix ground juniper (if using), ⅓ cup demerara sugar, and ⅓ cup granulated sugar in a small bowl.
Punch down dough and turn out onto a lightly floured surface; divide into 3 pieces. Working with 1 piece at a time and keeping the other pieces covered in plastic wrap, roll out dough into about a 12×8″ rectangle. Sprinkle with one-third of sugar mixture and cut crosswise into 4 pieces (you should have four 8×3″ rectangles). Roll up each piece to make a long rope; squeeze ends gently and pinch along seam to seal. Tug rope to stretch so it’s about 10″ long, then tie into a knot. You should end up with 12 buns.
Arrange buns in prepared pan to make a 4×3 grid and brush with melted butter. Sprinkle with demerara sugar and cover loosely with plastic wrap. Let sit until buns look puffed and lightly hold the imprint of a finger when gently pressed, 50–70 minutes. Bake until buns are golden brown and sugar is caramelized, 15–20 minutes. Turn out of baking dish onto a wire rack and let cool slightly.