Warm the milk and 6 tablespoons butter on the stovetop or in the microwave until butter is melted. Set aside and allow to cool until warm, but not too hot to touch (120-130°F).
In the bowl of a stand mixer fitted with a paddle attachment, add 4 cups flour, yeast, brown sugar, salt and pumpkin pie spice. Stir to combine. Add the eggs, pumpkin pureé, warm water and milk/butter mixture. Mix on medium-low speed until combined, and then switch to the dough hook.
Add enough of the remaining flour, 1/2 cup at a time, until the dough is less sticky and starts to pull away from the bowl. Knead until dough is soft and smooth, about 3-5 minutes. Place dough in an oiled bowl; cover with plastic wrap or a clean, damp towel. Allow dough to proof in a warm space for about an hour, or until dough as doubled in size.
Punch down dough and turn out onto a floured surface. Roll into approximately a 12x16-inch rectangle. Divide the dough into equal rectangles, about 2x4-inch size. (I divided mine into 32, but you could do 24-36 depending on how big you want them.)
Using about 2 tablespoons of melted butter, brush butter on each rectangle. Fold rectangle in half, leaving about a 1/2-inch gap on the bottom. Place first roll, smooth-side up, on a quarter sheet pan or a 9x13-inch baking dish. Repeat with remaining rolls, overlapping them brick-style (or like roof shingles).
Cover rolls and let rise for 20-30 minutes.OR place the whole pan in the fridge (for up to 12 hours), bringing back out to room temp for 20-30 mins before baking.
Preheat oven to 350°F.
When rolls are done rising, uncover and bake for 20-24 minutes, or until rolls are golden brown.
Top with remaining melted butter and sea salt (or honey butter, or a drizzle of maple syrup). Serve warm.