1. Prepare the dough. In a medium saucepan over medium-high heat, melt the butter. Once melted, slowly pour in the milk, and stir to combine. Once the mixture is heated through and hot to the touch. remove from heat.
2. In the bowl of stand mixer fitted with the dough attachment, or in a large mixing bowl, pour in the warm butter and milk mixture. Sprinkle the yeast over top and give it a stir to combine. Allow it to sit for 5 minutes or until foamy “proofing the yeast”.  Add the egg, honey, salt and flour. Turn the mixer on low until all of the ingredients are combined and a ball begins to form, then turn it to medium/high and run it for 5-6 more minutes. If not using a stand mixer, stir the mixture with a large wooden spoon until combined, then knead by hand on a lightly floured surface for 4-5 minutes. Transfer the dough to a large bowl, cover and allow it to rise in a warm environment for 1 1/2 – 2 hours, or until doubled in size.
3. Prepare the rhubarb compote. In a medium size saucepan over medium heat, combine the chopped rhubarb, honey, lemon juice and cornstarch. Heat the mixture to boiling, stirring occasionally. Once the mixture is boiling, turn it to low and allow it to simmer until thickened, about 10 minutes. Use the back of your spoon to break up the larger pieces. Remove the compote from heat and transfer it to another bowl, then place in the fridge until ready to use, or about 1 hour.
4. Prepare the streusel. In a medium sized mixing bowl, combine the cubed butter, rolled oats, coconut sugar, flour and cinnamon. Use a pastry cutter or a fork to cut up the mixture until it forms pea-like crumbs. Set aside.
5. Once the dough has completed the first rise, lightly dust a work surface with flour and empty the dough onto the work surface. Using a floured rolling pin, roll out the dough into a 12×18 rectangle (I use my measuring tape)! Remove the filling from the fridge, and reserving 1/2 cup, apply the filling all over the dough, leaving about 1 inch on all sides. Scatter the streusel evenly across the dough and on top of the filling. Roll up the dough tightly on the long edge into an 18″ log. There might be a bit of spillage, but that’s ok. Cut the log into 12 equal pieces and place the pieces, cut side up, into a greased cast iron skillet or 9×13″ pan. Cover the pan tightly with saran wrap or aluminum foil. Place in a warm environment for a second rise, about 1-2 hours (or overnight – see notes)*.
6. Prepare the glaze. In a small mixing bowl, combine the reserved rhubarb compote, powdered sugar and a squeeze of lemon. Whisk to combine, then add 1 tbsp of whole milk to thin it out. If you’d like it thicker, add a bit more powdered sugar, or a bit more milk to thin it out more.
7. Preheat the oven to 350 F. Once the rolls are nice and puffy, remove the saran wrap or aluminum foil and place in the oven for 25-30 minutes or until lightly browned. Check the rolls after 15 minutes, and if the tops are becoming too brown, cover the pan lightly with aluminum foil for the remaining cook time.
8. Remove the rolls from the oven, and smother them with glaze. Serve immediately!

Leftover rolls can be kept in the fridge, in an airtight container for 3-4 days.