In a large bowl, combine warm water (or milk), honey, and yeast. Let sit 5–10 minutes until foamy.
Mix the Dough
Add sourdough discard, melted butter, and salt. Stir to combine. Gradually add flour until a soft dough forms.
Knead
Turn dough onto a lightly floured surface and knead for 8–10 minutes until smooth and elastic. Dough should be soft but not sticky.
First Rise
Place dough in a greased bowl, cover, and let rise in a warm spot for 1½-2 hours, until doubled in size.
Shape
Gently deflate the dough and shape into a loaf. Place into a greased loaf pan or shape into a rustic round on a baking sheet.
Second Rise
Cover and let rise for 30–45 minutes, until puffy.
Bake
Preheat oven to 400°F (204°C). Sprinkle flour on the top of the dough and score. Bake for 35–40 minutes, until golden brown and the loaf sounds hollow when tapped.
Cool
Remove from pan and cool completely on a wire rack before slicing.
Notes
Milk creates a softer crumb; water gives a slightly chewier loafDiscard can be used straight from the fridgeSubstitute up to 1 cup whole wheat flour for extra rustic flavorBrush the loaf with butter while warm for a soft, golden crust