Combine yeast, 1 tsp sugar and warm water in a bowl and set aside for 5 minutes. Meanwhile whisk together eggs, vanilla, brown sugar, salt, sugar, pumpkin, butter and spices in a separate bowl. Yeast should be starting to foam.
Add the flour and yeast mixture to the bowl and begin mixing. Knead for 20 minutes until dough is smooth an elastic-y. Allow to rise 40-60 minutes, only until doubled in size.
Make filling while dough rises. Place the butter and milk in a saucepan over medium heat., just until the butter is melted. Turn off heat and mix in egg yolk, cocoa, sugar and flour. Set aside to cool.
SRoll dough 1/8" thick. Spread chocolate across dough. Roll up from a short end. Cut in half lengthwise then fold the halves over and under to create a twist. Rise 20 more minutes then bake at 350*F for 35 minutes.