Measure ingredients for the tangzhong roux (milk, butter, flour), set aside.
Measure all ingredients separately for the dough, set aside.
Add milk and butter to the saucepan together and heat over medium heat just until the butter is melted.
Add flour to the hot milk mixture and stir constantly with a spatula for 3 minutes to heat the flour through making a thick blond roux (mix constantly and do not overheat as the mixture will begin to caramelize/darken then it can burn). The mixture will look like mashed potatoes.
Remove from heat and set aside for 10 minutes to cool.
While mixture is cooling, mix yeast and warm water with a pinch of sugar until foamy.
Using an electric stand mixer with paddle attachment mix pumpkin puree and roux together at medium speed using paddle attachment until thoroughly combined, scrape sides of bowl as needed.
Add yeast mixture and sugar to the mixer bowl and mix on low until combined, scrape sides of bowl.
Switch to dough hook. Add salt, pumpkin pie spice and flour. Mix on low speed until a rough dough comes together (about 2 minutes).
Switch to speed two and continue to mix until a wet dough is formed about 5 more minutes. Scrape down sides as needed. Dough will climb up dough hook and stick to bottom when its done mixing.
Generously flour a flat work surface. Remove dough from bowl to floured surface. Knead a few times just to form a smooth ball.
Spray a bowl with oil. Place dough into bowl, cover with plastic or kitchen towel, and allow to rise until doubled.
Mix softened butter & pumpkin puree together to make pumpkin butter, set aside.
Mix spices and brown sugar together, set aside.
Once dough has doubled, dump dough onto a floured work surface.
Roll dough out to a 12" x 18" rectangle (long side facing you).