Feeding the Starter: Remove 25 grams of sourdough starter from the fridge. Mix with 25 grams whole grain spelt flour and 25 grams water in a glass jar. Stir well until no dry flour remains. Cover and mark the jar, let sit at room temperature for 4-12 hours until it doubles in size. The First Rise: Once starter has doubled, combine bread flour, whole grain spelt flour, water, salt, and 50 grams active starter in a mixing bowl. Stir until no dry flour remains; add a spoonful of water if dough feels dry. Cover and let rest 30 minutes. Stretch and Folds: Perform first set of stretch and folds by stretching each side (north, south, east, west) over the dough. Rest dough 30 minutes. Repeat stretch and fold two more times with 30-minute rests in between. After third fold, cover and let rise at room temperature until dough doubles in size (5-10 hours). Shaping: When doubled, sprinkle flour and flip dough onto counter. Flip sticky side down, pull edges to form a ball. Rest uncovered for 20-30 minutes. Final shape: Sprinkle flour on top, flip so floured side down, flatten dough into a rectangle. Roll into a log shape and place seam-side down in loaf pan. If pan isn't non-stick, line with parchment paper. The Second Rise: Cover dough and refrigerate overnight or 8-12 hours to extend fermentation. Remove from fridge and let rise at room temperature until doubled and puffed over pan. Baking: Preheat oven to 450°F 30 minutes before baking and place a metal pan on bottom rack. Place loaf on middle rack and pour a cup of hot water into the bottom pan to create steam. Bake 20 minutes, remove steam pan, reduce oven to 400°F, and bake 15-20 more minutes until the internal temperature reaches 190°F. Cooling: Remove bread from pan and cool on wire rack for at least one hour before slicing.