• Flour mixture: In a large bowl, whisk together the flour, yeast, salt, sugar, orange zest, and poppy seeds.
• Milk mixture: In another bowl, whisk together the warm milk, warm water, melted butter, and egg.
• Combine: Pour the milk mixture into the flour mixture. Stir with a spatula until a soft, sticky dough forms.
• First rise: Cover the bowl and let the dough rise in a warm place for 45–60 minutes, or until it has roughly doubled in size.
• Shape: Sprinkle about ¼ cup flour onto your work surface. Turn the dough onto the floured surface and lightly dust the top with flour. The dough will be quite sticky after rising, so use a spatula to gently fold it over a few times, adding just enough flour until it's easier to handle.
• Press or roll the dough into a rectangle about 10 × 12 inches (25 × 30 cm).
• Cut the dough: From the short side, cut the dough into 4 strips, each about 2½ inches (6 cm) wide. From the long side, cut the dough into 5 rows, about 2½ inches (6 cm) apart, to create 20 square pieces.
• Second rise: Arrange the dough squares on a parchment-lined baking sheet, leaving about 1 inch (2.5 cm) between each one. Lightly tuck in the corners of each square for a softer, pillowy shape. Cover loosely and let them rise at room temperature for 20 minutes.
• Preheat the oven to 350°F (180°C) or 160°C fan.
• Bake for 18–20 minutes, until lightly golden.
• Orange butter: While the buns bake, stir together the melted butter, orange juice, orange zest, and sugar until well combined.
• Brush the warm buns with the orange butter as soon as they come out of the oven.

Storage

• Store in an airtight container at room temperature for up to 2 days. Warm in the microwave for a few seconds or in a 300°F (150°C) oven for 5–8 minutes.