Whisk the warm milk, yeast, and 15 ml of granulated sugar together in a small bowl. Let sit undisturbed for 8 to 10 minutes until a foamy head develops on top.

In the bowl of a stand mixer fitted with the dough hook, combine the foamed yeast mixture, remaining granulated sugar, eggs, melted butter, fine salt, and 0.5 teaspoon ground cinnamon. Add 720 ml of flour and mix on low speed until combined, then gradually add the remaining flour. Knead on medium speed for 6 to 8 minutes until a smooth, pliable dough forms that springs back when pressed.

Lightly oil a clean large bowl, transfer the dough ball into it, and turn once to coat the top. Cover tightly with a clean damp kitchen towel and let rise in a draft-free warm spot for 60 minutes, or until doubled in size.

Turn the proofed dough out onto a lightly floured counter and gently roll it into an even 12x18-inch rectangle. Spread the softened butter over the surface, leaving a half-inch border clean along the top edge. In a bowl, blend the packed brown sugar, 30 ml ground cinnamon, and nutmeg, then distribute the mixture evenly over the butter.

Roll the dough tightly from the long bottom edge into a neat 18-inch cylinder and pinch the seam securely closed. Trim off the uneven tips, then divide and slice the log into 8 equal rounds using unflavored dental floss or a sharp knife.

Moisten the pre-cut lengths of butcher twine with a light rub of neutral oil to prevent sticking. Arrange 4 strands of twine into an 8-spoke wheel pattern, place a cinnamon roll cut-side down in the center, and gather the string ends over the top, tying them loosely with a knot. Do not tie snugly, as the dough requires room to swell into pumpkin segments.

Transfer the tied rolls onto a large baking sheet lined with parchment paper, leaving at least 2 inches between each roll. Cover loosely with greased plastic wrap and let rise for 20 to 25 minutes until puffed. Preheat your oven to 350 degrees F (175 degrees C).

Bake in the preheated oven for 20 to 22 minutes, or until the rolls turn golden brown and sound hollow when lightly tapped. Remove from the oven and allow to rest on the sheet pan for 10 minutes.

While the rolls are warm to the touch, carefully snip the top knots with kitchen shears and peel away all strands of twine. Whisk together the powdered sugar, milk, and vanilla extract in a small bowl until smooth. Drizzle glaze over each roll and press a pecan half firmly into the center indentation to serve as a pumpkin stem.