In a large bowl, whisk together the 4 cups flour, ⅓ cup granulated sugar, 2¼ teaspoons instant yeast, and 1 teaspoon salt.
Add the 1 cup warm milk, ⅓ cup melted butter, and 2 eggs. Mix until a shaggy dough forms, then knead for about 8 minutes by hand or 5 minutes in a stand mixer, until smooth and elastic.
Place the dough in a greased bowl, cover, and let it rise in a warm spot for 1 hour, or until doubled in size.
While it rises, make the filling. Stir together the ½ cup softened butter and ¾ cup Biscoff spread until smooth and spreadable.
Punch down the dough and roll it out on a floured surface into a 16 by 12 inch rectangle.
Spread the Biscoff butter mixture evenly over the dough, right to the edges. Sprinkle the ½ cup brown sugar and 1 tablespoon cinnamon over the top, then scatter on the ⅓ cup crushed Biscoff cookies.
Starting from a long edge, roll the dough up tightly into a log. Cut it into 12 even rolls and place them in a greased 9 by 13 inch baking dish.
Cover and let the rolls rise again for 45 minutes, until puffy. Near the end of the rise, preheat your oven to 350°F (175°C).
Just before baking, slowly pour the ½ cup warmed heavy cream over the risen rolls, letting it pool in the gaps between them. Bake for 22 to 25 minutes, until golden and cooked through. Let them cool for 10 minutes before icing, because hot rolls will melt the icing right off.
For the icing, beat the 4 ounces cream cheese, ¼ cup butter, and ⅓ cup Biscoff spread until smooth. Add the 1 cup powdered sugar, 1 teaspoon vanilla, and 2 tablespoons milk, and beat until creamy.
Spread the icing over the warm rolls. Top each roll with a whole Biscoff cookie, and sprinkle the ¼ cup crushed Biscoff cookies over everything for crunch.