Prepare the dough by combining all-purpose flour, instant yeast, and granulated sugar in the bowl of a stand mixer or a large mixing bowl; add warmed whole milk, large eggs, softened unsalted butter (dough), and fine salt, then mix until a shaggy dough forms, adding water a tablespoon at a time only if the dough is too dry.

Knead the dough on medium speed with the dough hook for 6–8 minutes until smooth and elastic, or knead by hand for 8–10 minutes until the dough passes a gentle windowpane test.

Lightly oil a bowl with vegetable oil or melted butter, place the kneaded dough in the bowl, cover, and let rise until doubled, about 60–90 minutes, or refrigerate for 8–12 hours for a slow fermentation.

While the dough rises, prepare the filling by whisking brown sugar and ground cinnamon together, then pouring melted unsalted butter (filling) over the mixture and stirring to form a spreadable paste.

Turn the risen dough onto a floured surface and roll to a 12x16-inch rectangle about 1/4 inch thick; trim the edges so the rectangle is even.

Spread the cinnamon-brown sugar filling evenly across the dough with an offset spatula, leaving a 1/2-inch clean border along the far long edge to prevent overflow.

Roll the dough tightly from the long edge nearest you into a log, pinch the seam to seal, wrap in plastic, and refrigerate at least 30 minutes to firm for cleaner slicing.

Remove the chilled log and slice into 3/4–1-inch rounds using a serrated knife or dental floss; target 16–18 slices for a compact tree or 20+ for a taller tree.

Grease a parchment-lined baking sheet or a 9x13-inch pan with vegetable oil or melted butter and arrange the slices in rows forming a triangle: one at the top, two below, then three, and so on until you have a tree shape.

Cover the arranged tree and proof for 30–45 minutes until puffy and nearly touching; preheat the oven to 350°F (175°C) during the last 15 minutes of proofing.

Bake the tree on the middle rack for 20–25 minutes until golden brown; if the tops brown too quickly tent loosely with foil for the final minutes of baking.

Optional: brush the hot rolls with 1–2 tablespoons of melted unsalted butter for shine and extra richness, then cool for 8–12 minutes so the glaze won’t run.

Whisk together powdered sugar, vanilla extract, and 2 tablespoons whole milk or cream to make a thick, pourable glaze; thin with additional milk if necessary.

Drizzle the glaze over the warm tree, then immediately sprinkle with dried cranberries, red and green sanding sugar or sprinkles, and chopped pecans or walnuts so they adhere to the glaze.

Serve warm for pull-apart enjoyment; to reheat chilled or frozen rolls, warm in a 300°F (150°C) oven covered with foil for 8–15 minutes depending on size, then glaze before serving.