In a large bowl, combine the flour, sugar, dry yeast, salt, and cinnamon.
Add the milk, water, eggs, pumpkin purée, and melted butter. Mix to combine and knead until the dough is soft, slightly sticky but elastic enough to detach from the sides of the bowl.
Transfer the dough to an oiled bowl, cover with plastic wrap, and let rise for about 1 hour in a warm place until doubled in size.
Pound down the dough and divide into 2 equal parts. Form into balls. On a floured surface, roll each part into a 38-40 cm circle using a rolling pin.
Using the back of a spoon or spatula, spread 2 tablespoons (30 g) of softened butter on each rolled-out dough.
Using a cutter, cut 12 equal triangles (like slicing a pizza).
Make a small slit in the center of each triangle base.
Roll each triangle into a half-moon, starting from the outer edge of the triangle.
Once rolled, place on a lined baking sheet with the point facing down and underneath the roll. Repeat with the remaining triangles.
Cover with a towel and let rise for about 20-30 minutes.
Meanwhile, preheat the oven to 200°C.
Bake the half-moon rolls for 14-18 minutes until puffed and golden.
While still hot, melt another 1½ tablespoons (20 g) of butter and brush over the top of the rolls.
Let cool for a few minutes before serving.