01 - Combine flour, sugar, yeast, and salt in a large mixing bowl. Whisk thoroughly to distribute yeast evenly.
02 - Pour warm milk, warm water, melted butter, and cracked egg into the dry ingredients. Stir until a shaggy, sticky dough forms.
03 - Turn dough onto a lightly floured surface. Knead for 8-10 minutes until smooth and elastic, or use a stand mixer with dough hook for 6-7 minutes on medium-low speed.
04 - Place dough in a greased bowl, turning once to coat all sides. Cover with plastic wrap or a clean towel. Let rise in a warm, draft-free area for 1 hour until doubled in size.
05 - Punch down risen dough to release air. Roll into a 16x12-inch rectangle on a lightly floured surface, maintaining even thickness throughout.
06 - Beat softened butter and Biscoff spread in a small bowl until completely smooth and combined. Spread evenly over the rolled dough, leaving a 1/2-inch border. Sprinkle brown sugar and cinnamon uniformly across the surface.
07 - Starting from the long edge, roll dough tightly into a log. Use a sharp knife or unflavored dental floss to slice into 12 equal portions, approximately 1 1/2 inches thick.
08 - Arrange rolls cut-side up in a greased 9x13-inch baking dish, leaving slight space between each. Cover loosely and let rise for 45-60 minutes until puffy and nearly doubled.
09 - Position oven rack in the center. Preheat to 350°F.
10 - Bake for 22-25 minutes until golden brown on top and cooked through. The center should reach 190°F when tested with an instant-read thermometer.
11 - Whisk melted Biscoff spread, powdered sugar, and 2 tbsp milk in a small bowl until completely smooth. Add additional milk 1 tsp at a time if needed to reach drizzling consistency.
12 - Drizzle warm glaze generously over immediately baked rolls. Serve warm for best texture and flavor.