In a large container or bowl, stir together ⅔ cup spelt flour, ⅓ cup water, and yeast until a smooth paste forms; cover with plastic wrap, and let sit for 24 hours. Repeat this process for the next eight days, adding ⅓ cup plus 1 tbsp. spelt flour and 2 tbsp. water each day to make the starter (which you can keep alive, in the fridge, by adding the same amounts once weekly).
On the 10th day, place ¼ cup starter in a large bowl and stir in ½ cup water (_Figure A_); add 1 cup spelt flour and stir until smooth to create the sourdough culture; let sit for 8-24 hours, until ready to bake.
Uncover sourdough culture and add remaining 2 ¾ cups spelt flour and ½ cup plus 2 tbsp. water, along with honey and salt (_Figure B_), and stir with a fork until dough forms and all flour is absorbed. Transfer dough to a lightly floured work surface, and knead until smooth and elastic, about 10 minutes. Transfer dough ball to a lightly greased bowl; cover bowl with plastic wrap, and place bowl in a cold oven. Let dough rest until doubled in size, about 3 hours.
Transfer dough to a lightly floured work surface, and flatten slightly. Fold the top and bottom edges toward the middle (_Figure D_), as if you were folding a letter; this action evenly distributes the air pockets so the bread will rise evenly. Place dough, seam side down, into a greased 8″ x 5″ x 2 ½″ loaf pan (_Figure D_); cover with plastic again, and return to oven. Let sit until doubled in size and dough reaches the top of the loaf pan, 2-3 hours. One hour before baking, remove loaf pan with dough from oven and place a cast-iron skillet on bottom rack. Position another rack above skillet and place a baking stone on it. Heat oven to 400°.
Lightly dust the top of loaf with all-purpose flour, and using a sharp razor or paring knife, slash the top of the loaf at a 30° angle in four spots; each slash should be about 4″ long. Place loaf on baking stone; place ice cubes in skillet. Bake until dark brown and crisp, about 40 minutes; let cool before serving.