Preheat your oven to 350°F and line a baking sheet with parchment paper.
In a large bowl, whisk together the melted butter, brown sugar, and granulated sugar until well combined.
1/2 cup butter, 3/4 cup brown sugar, 1/4 cup granulated sugar
Add the egg, vanilla extract, and sourdough discard, and mix until smooth.
1 large egg, 1 teaspoon vanilla extract, 1/2 cup sourdough discard
In a separate bowl, sift together the bread flour, all-purpose flour, baking soda, baking powder, and salt.
1 cup bread flour, 1 cup all-purpose flour, 1/2 teaspoon baking soda, 1/2 teaspoon baking powder, 1/2 teaspoon salt
Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Fold in the chocolate chips. Cover the dough and chill for an hour before baking.
1 cup chocolate chips
Scoop the dough onto the prepared baking sheet, using about 3 tablespoons of dough per cookie and spacing them about 2 inches apart. Top with extra chocolate chips then bake for 10 minutes or until the edges are set but the center is still soft.
Allow the cookies to cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.