In a large mixing bowl, combine 4 cups of all-purpose flour, 1/4 cup of granulated sugar, 1 teaspoon of salt, and 2 1/4 teaspoons of instant yeast. Gradually pour in 1 cup of warm milk, an egg, and 1/2 cup of softened unsalted butter. Mix until a shaggy dough forms, then knead on a floured surface for 7-10 minutes until smooth and elastic.

Transfer the kneaded dough into a greased bowl and cover with a damp cloth. Let it rise at room temperature for around 2 hours or until doubled in size.

Punch down the risen dough and roll into a 16 by 12-inch rectangle. Spread 1 cup of Biscoff spread evenly on top, leaving a small border.

Sprinkle 1/2 cup of crushed Biscoff cookies over the spread. Roll the dough tightly from the long edge into a log shape and slice into 12 equal pieces.

Place the rolls cut-side up in a greased baking dish and cover with a clean kitchen towel. Let them rise for about 1 hour.

Preheat your oven to 350°F (180°C). Bake the rolls for approximately 25 minutes or until golden brown.

Prepare frosting by whipping together 4 oz of softened cream cheese, 1/4 cup of softened butter, 1/2 cup of Biscoff spread, 1 1/2 cups of powdered sugar, and 1 teaspoon of vanilla extract until smooth.

Once the rolls are out of the oven, let them cool slightly and spread the frosting generously over the warm rolls.