In a glass 2-cup measuring cup, warm the milk in the microwave for 45 seconds on high. Sprinkle in the yeast and 2 tbsp. of sugar (subtract it from the ½ c. of sugar listed in the rolls section above) and mix gently. Let the mixture stand for 5 minutes or until it is bubbly and foamy.
Meanwhile, combine the remaining sugar, butter, eggs, salt, extract, and zest in the bowl of a stand mixer fitted with the paddle attachment. Mix for 15 seconds or until the mixture is just combined. Once the yeast/milk mixture is bubbly, with the mixing speed on low, alternate the liquid and flour (use 4½ c. and then add the extra ½ c. if needed) until combined.
Switch to the hook attachment and knead the dough on the lowest speed for 6-8 minutes or until it is smooth and firm. Remove the dough from the bowl and place it into a large, lightly greased metal or glass bowl. Cover tightly with plastic wrap and allow to rise for 1½ hours.
Once the dough has risen, roll it out into a large rectangle. Spread butter on top, then marmalade. In a small mixing bowl, combine the brown sugar, cinnamon, vanilla, and orange zest. Sprinkle this on top of the butter/marmalade mixture. Roll the dough lengthwise into a large log. Using plain dental floss, cut in half, then continue by cutting each section in half and repeating (I do it this way to get even cuts and an even amount of rolls).
Place the rolls into a 12×17 inch baking sheet (you will want to use baking spray to prevent them from sticking to the bottoms and sides), leaving at least an inch around each roll. Cover with plastic wrap and allow to rise for 30 more minutes.
Once the rolls have risen, place them in the oven at 400 degrees Fahrenheit (204 degrees Celsius) for 18-20 minutes or until golden brown on top.
While the rolls bake, prepare the glaze by combining all ingredients in a large bowl and mixing until smooth.
Remove the rolls from the oven and allow them to cool for 15 minutes before pouring the frosting over the top. Spread the frosting evenly. Allow to sit for an additional 10 minutes before serving.