Apple Butter Thumbprint Cookies Recipe

Ingredients

• ¾ cup finely ground black walnuts
• 1¾ cup all-purpose flour
• ½ cup buckwheat flour
• ½ teaspoon fine salt
• 2 large eggs, beaten
• 1 teaspoon vanilla extract
• 1 cup (2 sticks) unsalted butter, soft and room temperature
• ¾ cup sugar, divided
• 1 cup apple butter