In a mixing bowl whisk together egg, honey, sourdough starter.
Then trickle in milk and cooled, melted butter while whisking. Once combined throughout, mix in flour and salt, a little at a time. You may need to switch to a spatula.
Once the dough has achieved a sticky ball (it does not need to be smooth) and the flour is no longer visible, scrape down the sides and cover for 30 minutes.
If you have a mixer, use a dough hook to knead the dough on low speed (#2 on Kitchen Aid stand mixer), or hand knead for 5-7 minutes or until dough is soft and you can pinch the dough and pull it about 2” away. If you knead it too long it will likely break apart before 2” and if you haven't kneaded it long enough it will be too squishy to pull.
Cover with plastic wrap for 8-12 hours for bulk fermentation, 1st proof. Room temp determines time. If less than 70 degrees in the house it will take closer to 12 hours. You can put it in the oven with the light on and door closed, or on top of the fridge for a warmer spot, but watch it carefully so it doesn’t overproof. See notes for alternative schedules.
Dough is proofed when it has doubled in size and appears to be glossy and supple dough. Grease your baking dish (8" or 9" pan, cast iron pan, glass dish or pie plate would all work).
Turn out onto well floured surface and roll to 14” x 10” rectangle that is about 1/2” thick -- it does not have to be a perfect rectangle, try your best.
Using the back of a spoon spread the pear butter over the surface of the dough, leaving a 1/2 inch margin on the shorter sides and on one of the long sides. Get the filling as close as possible to the edge on other long side.
Sprinkle with brown sugar and cinnamon. Use spoon to press the sugar and cinnamon down if needed.
Begin rolling the dough with the long edge. Start on the side that has the filling all the way to the edge and roll tightly. Use a bench scraper if dough is sticking to counter, don't pull it. Roll all the way and with the seam facing up, pinch the seam closed.
Trim the 2 ends using a bench scraper so that the roll is even in thickness throughout. Score the remaining log into 8 even rolls. Use a greased bench scraper to cut confidently and quickly. Place the rolls immediately into greased pan.
Once rolls are placed in the pan, breathe a sigh of relief, the hardest part is over! Now cover with plastic wrap and allow to proof/recover. Again depending on room temperature could take 30 minutes to 2 hours. You will know it is ready when rolls are touching each other, and the dough appears puffed up.
Preheat oven to 350F when rolls are almost done rising. Place in oven for 35 minutes or until golden brown on the top. Allow to cool in pan, this allows the filling to be re-absorbed into the dough after baking.