• In a small saucepan, warm the water, milk, and sugar to 100-110℉. Do not overheat.
• Stir in the yeast. Allow to rest for 5-10 minutes until the yeast comes to the surface and appears frothy.
• Add the flour, sourdough starter, and yeast mixture to the bowl of a stand mixer fitted with the dough hook attachment. Mix on low for 5 minutes.
• Add the butter and salt and continue to mix for another 5 minutes.
• Cover the bowl and allow to rest until the dough appears doubled in size (about 1-1.5 hours).

Shape the Dough

• Line a 9x8 inch baking pan with parchment paper, then spray with cooking spray. Set aside.
• Trasnsfer the dough to a clean work surface. Gently pull the dough into a rectangle that is roughly double the length of the baking pan.
• Fold the dough in half so it is now the width of the baking pan. Roll the dough into a log and place in the prepared baking pan. Cover and allow to rise until the dough comes 1 inch above the edge of the baking pan (about 1-1.5 hours).
• When bread is nearly done rising, preheat oven to 350℉.
• Bake bread in preheated oven for 33 minutes.
• Remove from oven and allow to cool in pan for 30 minutes. Remove from pan and allow to cool completely on a wire rack.