(With chocolate and apricot almond variations)
¼ cup butter
4 cups flour
¼ cup sugar
2 teaspoons salt
1¼ cup milk
½ cup sourdough starter
Butter layer:
1½ cup unsalted butter
Egg wash:
1 large egg yolk mixed with 1 tablespoon water.
In bowl of a stand mixer, combine all ingredients. Using a dough-hook attachment, knead until it is glossy and stretchy, and pulls away from sides bowl easily, about 10 minutes. Transfer to a greased bowl and cover tightly. Allow to rest overnight. Refrigerate for 1 hour. Place on a lightly floured surface and roll out to a 10 x 16-inch rectangle. Cover and chill for 4 hours. Meanwhile, cut unsalted butter sticks into fourths and place on a sheet of parchment paper. Roll butter out to form an 8 x 10-inch rectangle. Remove dough from refrigerator and place butter layer in center of dough. Fold sides over butter and roll out again to form a 10 x 16-in rectangle. Cover and chill for 4 hours. Turn dough and fold into thirds again and roll out again to form rectangle. Repeat fold-roll-chill process 2 more times. Place dough on a lightly floured surface and roll out to a 10 x 20-inch rectangle. Cut into 12 (4-inch) triangles. Preheat oven to 375 degrees. Place rolled dough on a baking sheet and brush with egg wash. Bake for 30 minutes or until golden brown.
For the chocolate croissants, divide 4 ounces of chopped chocolate between 12 unrolled croissants. Place chocolate at wide end and roll up. Bake as directed and drizzle melted chocolate if desired.
For Apricot-Almond croissants, whisk 4 ounces of apricot jam with 2 tablespoons butter over low heat until melted. Brush croissant dough with melted jam and sprinkle with sliced almonds. Bake as directed.