Be sure to view images in post above for visuals for each step!
Preheat oven to 350°F.
Use a citrus zester to zest 2-3 large navel oranges, or until you have about 1½ tablespoons of zest. Divide zest into two bowls; one with 1 tablespoon and the other with 1 teaspoon. Once fully zested, cut oranges in half and squeeze out the juice (you want at least ½ cup for the dough + 1 tablespoon for the frosting). Set aside. In a small microwave-safe bowl, melt unsalted butter (¼ cup, i.e. ½ stick) for 45 seconds, or until fully melted. Pour into a larger, medium-sized bowl. Using that same small bowl you just microwaved the butter in, pour in milk (½ cup) and microwave for 45 seconds. Once done, pour milk in with the butter.
Add in yeast (2¼ teaspoon, i.e. 1 packet) and granulated sugar (¼ cup) and stir with a whisk until dissolved. Cover with a clean dish towel or plastic wrap and let sit for 10 minutes until it is foamy.
Once your dough starter has been sitting for 10 minutes, mix in the freshly squeezed orange juice (½ cup), egg (1 large), salt (½ teaspoon), and vanilla extract (1 teaspoon).
Once combined, start adding in all-purpose flour (3½ cups), one-cup at a time. You should be able to mix this with a spatula until you get to the end of adding the flour. At that point, you will need to use your hands. Keeping the dough in the bowl, gently form it into a ball. If dough is sticky, sprinkle 1 tablespoon of flour to the outside. Cover and let sit for 10 minutes (while waiting, proceed to next step to make filling).Tip: Don't force any extra flour from the bottom of the bowl into the dough, unless the dough feels sticky. It's okay to have a little bit left. While the dough is resting, go ahead and mix up the orange cinnamon filling! To do so, mix together softened butter (½ cup, i.e. 1 stick), light brown sugar (½ cup), granulated sugar (½ cup), cinnamon (2 tablespoons), orange zest (1 tablespoon), and vanilla extract (1 teaspoon). Set aside.Tip: You don’t want your butter to be super melted (just a little is okay!) or the filling will be more likely to seep through the bottom of the pan and crystallize. On the contrary, if your butter is too cold and isn't mixing well, you can use a mixer to whip it all together. After 10 minutes, place dough on a flour-covered surface (about ½ – 1 tablespoon flour). I prefer taping down a piece of parchment to my counter, but you can also roll directly on a clean countertop. Sprinkle a little flour on top of the dough and on the rolling pin, then roll the dough until it is approximately a 14×18” rectangle that is ¼” thick.
Once rolled, spread on cinnamon sugar mixture, making sure to spread it all the way to the outside edges. I recommend spreading a small amount first; if it is too cold to spread, simply microwave for 5-10 seconds to help warm up (being careful not to melt it!).
Now it’s time to roll! It’s important to roll vertically (i.e. start rolling at a SHORT side) so that your cinnamon rolls are nice & thick; this will ensure you yield 12. If you roll it the other way, they’ll be smaller and a bit dinky. You want to roll relatively tight, but not too tight. (See images in post above)
Once rolled, use a serrated edge knife to slightly “score” the tops so you know where to cut. Start in the center, then add slits in the center of those and then divide each of those sections into two parts. (See images in post above for a visual.)Tip: Using a serrated edge knife and cutting slowly in a sawing motion is important, as a normal knife will likely squish the dough. Place cut cinnamon rolls in a greased, parchment-lined 9×13 baking pan and bake at 350°F for 24-26 minutes until the tops are slightly golden brown. Allow to cool for a bit (10-15 minutes) before adding frosting to prevent the frosting from totally melting. If you plan to eat them later, wait to frost until they’re cooled for a prettier frosting presentation.