Pumpernickel Bread for Smørrebrød

2 Loaves
2 cups tepid water
¼ cup cider vinegar
½ cup molasses
1 ounce bittersweet chocolate, chopped
2 teaspoons instant espresso
½ cup warm water to bloom yeast
1 tablespoon active yeast
½ teaspoon sugar
3½ cups rye flour
1 cup rolled oats
2-3 cups white flour
In a small sauce pan, combine 2 cups of water, cider vinegar, molasses, bittersweet chocolate, and espresso. Heat until the mixture is steaming, and then stir until the chocolate is completely melted. Remove the pan from the heat and allow the mixture to cool completely. Reserve.
Measure the ½ cup warm water into the bowl of a stand mixer. Add the yeast and sugar and stir them into the warm water. Allow the mixture to sit for 5-10 minutes, or until it foams. (If it does not foam, toss the mixture, buy or borrow new yeast, and start over.)
Pour the cooled water-vinegar mixture into the bowl. Add all the rye flour and mix on low speed with the paddle attachment until the ingredients are thoroughly blended. Switch to the dough hook, and begin to add white flour in ½ cup increments. When the dough just begins to pull away from the sides of the bowl, stop adding flour. Knead the dough in the mixer for another 8-10 minutes.
Turn the dough out onto a board and knead by hand for another 2 minutes. Form into a ball, and place in a greased bowl. Cover with a clean kitchen towel and set the bowl in a warm place while it rises—about 1½ hours.
When the dough has doubled in bulk, punch it down, split it in half and form it into two loaves. Place the loaves into buttered 9” x 4” loaf pans. Smear the tops of the loaves with soft butter and cover loosely with plastic wrap and a kitchen towel. Allow to rise in warm place until the loaves have doubled in bulk.
While the bread is rising, heat your oven to 350°F.
When the loaves are ready to bake, dust them with a little flour, slash the tops with a sharp knife, and bake for 35-40 minutes. To check if the bread is done, let the loaf fall from the pan and tap the bottom of it sharply with your fingers. If it sounds hollow, it’s through baking.
Remove the bread from the pans and allow it to cool completely on a rack before slicing for smørrebrød, the open-faced Scandinavian sandwiches last seen on 1960s restaurant brunch tables but now reborn.