Cook 1/3 cup flour and 1 cup water in a small saucepan over medium heat, whisking constantly, until a thick paste forms (almost like a roux but looser), about 5 minutes.
Add cream and honey and cook, whisking to blend, until honey dissolves. Transfer mixture to the bowl of a stand mixer fitted with a dough hook. Let mixture cool until it is just warm to the touch and sprinkle yeast over top.
Let the yeast sit until it starts to foam. About 5 minutes. Add milk powder, salt, 2 eggs, and remaining flour. Knead on medium speed until dough is smooth, about 5 minutes.
Add 4 tablespoons of butter, a piece at a time, fully incorporating into dough before adding the next piece, until dough is smooth, shiny, and elastic, about 5 minutes. Coat a large bowl with nonstick spray and transfer dough to bowl, turning to coat.
Cover with plastic wrap and let rise in a warm, draft-free place until doubled in size, about 1 hour. Punch down dough and divide into two equal sized portions. Roll one of the halves of dough into a large rectangle. Spread four tablespoons of butter over the surface of the dough.
Mix together the sugars and cinnamon. Sprinkle half the mixture over top. Roll the dough into a spiral from the short edge of the rectangle to the other so that it forms a log the same length as your loaf pan. Place the dough into the greased loaf pan.
Cover with plastic wrap and let sit until it rises above the level of the pan. About 1 hour. Repeat with other half of the dough. Whisk together the other egg with 1 tablespoon of water brush over top of the loaves. Bake at 375 degrees for about 45 minutes, until the outer crust is a dark golden brown.
If the crust starts getting too dark, cover with tin foil. Let cool to room temperature before slicing. If glazing the bread, whisk together the glaze ingredients until smooth. Pour over the tops of the loaves.