Whisk yeast into warm water and let sit 5 minutes. Mix yeast with the eggs, half-and-half and vanilla.
Add 1 cup of flour, the sugar, and the salt. Using the dough hook, a wooden spoon, or rubber spatula, slowly add 2 cups of flour, then the butter, and finally add the remaining 4 cups of flour.
When the dough comes together in a smooth mass, place in a greased bowl.
Let rise at least 1 hour, until roughly doubled.
Turn the dough out onto a floured board and roll into a rectangle ½-inch thick.
Spread 12-ounces of room temperature butter on all but the top ⅕ of the rectangle.
Mix 2½ cups brown sugar with ¼ cup cinnamon, and spread it evenly over the buttered surface.
Starting at the side closest to you, roll the rectangle into a log and pinch the un-buttered edge to seal.
Using a bench cutter, sharp knife, or dental floss, cut 12 even slices.
Place on greased baking sheets and let proof until doubled in volume, about 45 minutes. Don't put them anywhere too warm or the butter will melt out. Meanwhile preheat oven to 320F.
Bake until golden brown, about 25-30 minutes. They will bake faster if you have a convection fan.