Soft Spelt Walnut Date Sourdough Boule

Steps

1. Evening before: give your sourdough starter its usual 1:1:1 feeding (kept separate from this recipe's ingredients) and leave it at about 75°F (24°C) for 4 to 8 hours, until doubled, bubbly and domed at its peak.
2. Prepare the add-ins and portions: toast the walnuts in a dry skillet over medium heat for 4 to 5 minutes until fragrant, cool, then chop. Chop the dates. Set aside about 10 g of the bread flour for dusting. Soften about 20 g of the butter for the dough and keep the remaining 5 g for brushing.
3. In a large bowl, mix the spelt flour, the remaining bread flour, the water and the milk until no dry patches remain. Cover and rest 30 minutes (autolyse). The dough is about 58% hydration from the water and 2% salt, with the milk and starter making it softer.
4. Add the sourdough starter and the salt to the dough and squeeze and fold until combined, about 3 minutes.
5. Add the softened portion of butter and work it in until the dough is smooth and glossy, about 3 minutes.
6. Bulk rise at about 75°F (24°C) for 4 to 5 hours. During the first 2 hours, do 4 sets of stretch-and-folds 30 minutes apart; on the second set, scatter in the walnuts and dates and fold until evenly spread. Spelt is delicate, so fold gently. Bulk is done when the dough has grown about 50%, feels airy and shows bubbles on the sides.
7. Dust the counter with half of the reserved bread flour, turn the dough out, pre-shape into a loose round and rest 20 minutes. Dust a banneton or towel-lined bowl with the other half of the reserved bread flour, shape the dough into a snug boule and place it seam side up inside.
8. Cover and cold proof in the fridge for 10 to 14 hours overnight, until puffy and a fingertip poke springs back slowly.
9. Next morning, preheat the oven to 400°F (200°C) with a baking sheet inside for 30 minutes.
10. Turn the boule onto parchment, score the top, and slide it onto the hot sheet. Bake 40 to 45 minutes until deep golden and the center reads 190°F (88°C), since the dough is enriched with milk and butter.
11. Melt the reserved 5 g of butter, brush it over the hot crust, then cover the loaf loosely with a clean towel as it cools to keep the crust soft.
12. Cool on a rack at least 2 hours before cutting into 12 slices.