Chocolate Thumbprint Cookie

Ingredients

• 2 ounces unsweetened chocolate finely chopped
• 2 cups unbleached all purpose flour
• 1/4 teaspoon salt
• 8 ounces salted butter at room temperature
• 1/2 cup granulated sugar
• 1/3 cup dark brown sugar firmly packed
• 2 large eggs separated, at room temperature
• 1 teaspoon vanilla extract
• 3 cups finely chopped pecans
• cocoa powder for dusting, optional
• 8 ounces semisweet chocolate finely chopped
• 2 teaspoons vegetable oil