1In a stand mixer bowl, add 4 cups of all-purpose flour, 0.5 cups of granulated sugar, and 0.75 teaspoons of fine sea salt. Whisk until thoroughly combined.
2Add 0.33 cups of unsalted softened butter and use forks to blend it in until thoroughly incorporated with the dry flour.
3Separately, mix 1 cup of lukewarm whole milk (around 100°F) with 2.25 teaspoons of instant yeast. Stir until dissolved.
4Add the yeast mixture, two whole eggs, and one egg yolk to the flour mixture. Let that mix on medium-low speed for about 2–3 minutes, until you get a nice smooth dough.
5Remove the dough from the stand mixer, and give it a little knead (30 seconds to 1 minute) to smooth it out and form the gluten structure. Then roll the dough into a light ball and place it in a greased bowl. Cover it with a damp towel or plastic wrap and let it rise at room temperature for 1.5 hours or until doubled.
6Mix together 1 cup of brown sugar, 1 tablespoon of muscovado sugar (optional), and 2.5 tablespoons of ground cinnamon until thoroughly combined.
7Lightly flour a work surface, punch down, and dump out your dough. Flatten and roll it into a large rectangle that’s a little over a quarter of an inch thick (about 27 inches long). Spread 0.33 cups of unsalted softened butter across the surface of the dough, then sprinkle the cinnamon sugar mixture evenly.
8Tightly roll the dough up from the bottom to the top to get a nice thick log, then slice it into 12 segments that are about 2 inches thick using a serrated blade with scalloped edges.
9Lightly grease a 9x13 baking dish and line the bottom with the cinnamon rolls, facing their tails towards each other. Cover lightly with plastic wrap, and let them rise at room temperature for about 30–45 minutes or until they are 1.5 times their original size.
10Remove the plastic wrap and bake the cinnamon rolls in a preheated oven at 375°F (190°C) for 15–20 minutes, until beautifully risen and golden brown.
11Meanwhile, prepare the cream cheese glaze by whipping 4 ounces of full-fat cream cheese on high speed until nice and smooth. Then blend in 0.75 cups of powdered sugar until completely smooth. Mix in 3 tablespoons of whole milk (you may need a little more). Add half of a vanilla bean scraped of its seeds (save the pod for later) and whisk until you’ve got a nice thick but still drizzling glaze.
12Once your buns are cooled but still warm, drizzle on the cream cheese glaze using all of it.