Step 1: In a large mixing bowl, combine the warm milk and 1 tablespoon of the granulated sugar. Sprinkle the active dry yeast over the top and let it sit for 5-10 minutes until foamy. If it doesn't foam, your yeast may be inactive.
Step 2: To the yeast mixture, add the remaining granulated sugar, melted butter, eggs, vanilla extract, and salt. Whisk until well combined.
Step 3: Gradually add the all-purpose flour, 1 cup at a time, mixing with a wooden spoon or a stand mixer with a dough hook until a shaggy dough forms. Continue mixing until the dough comes together.
Step 4: Turn the dough out onto a lightly floured surface and knead for 8-10 minutes until smooth and elastic. If using a stand mixer, knead with the dough hook on medium-low speed for 6-8 minutes. The dough should be soft and slightly tacky.
Step 5: Lightly grease a large bowl with oil. Place the dough in the bowl, turning once to coat. Cover with plastic wrap or a clean kitchen towel and let rise in a warm place for 1.5-2 hours, or until doubled in size.
Step 6: While the dough is rising, prepare the filling. In a small bowl, combine the softened butter, light brown sugar, and ground cinnamon. Mix until a uniform paste forms. Set aside.
Step 7: Once the dough has doubled, gently punch it down to release the air. Turn it out onto a lightly floured surface and roll it into a large rectangle, approximately 18x12 inches (45x30 cm) and about 1/4 inch thick.
Step 8: Evenly spread the softened Biscoff cookie butter over the entire surface of the dough, leaving a 1/2-inch border along one of the long edges.
Step 9: Evenly spread the prepared cinnamon sugar filling over the Biscoff layer, ensuring it covers almost to the edges.
Step 10: Starting from the long edge opposite the clean border, tightly roll the dough into a log. Pinch the seam closed to seal it securely.
Step 11: Using a sharp, un-serrated knife or dental floss, cut the log into 12 equal-sized rolls, each approximately 1.5 inches thick. Place the rolls in a greased 9x13 inch baking dish, leaving a little space between each.
Step 12: Cover the baking dish loosely with plastic wrap or a clean towel and let the rolls rise in a warm place for another 30-45 minutes, or until puffy and almost touching each other. During the last 15 minutes of this rise, preheat your oven to 375°F (190°C).
Step 13: Bake the rolls for 20-25 minutes, or until golden brown on top and cooked through. If they start browning too quickly, loosely tent with foil.
Step 14: While the rolls are baking, prepare the cream cheese frosting. In a medium bowl, beat together the softened cream cheese, softened butter, powdered sugar, and vanilla extract until smooth and creamy. If needed, add 1-2 tablespoons of milk or cream to reach desired consistency.
Step 15: Once the rolls are out of the oven, let them cool in the baking dish for 5-10 minutes. Generously spread the cream cheese frosting over the warm rolls. Serve immediately and enjoy your delicious Biscoff Stuffed Cinnamon Rolls!