Apple Coffee Cake

Bahan-bahan (10 porsi)

• 1 cup white whole wheat flour
• ¼ cup all purpose flour
• 1 teaspoon ground cinnamon
• ½ teaspoon baking soda
• ½ teaspoon kosher salt
• ¼ teaspoon allspice
• ¼ teaspoon ground nutmeg (freshly grated if possible)
• ¼ cup unsalted butter (softened)
• ½ cup granulated sugar
• 1 large egg (at room temperature)
• 1 teaspoon vanilla extract
• ½ cup low-fat buttermilk (at room temperature)
• 1 ½ cups tart apples (peeled and diced, such as Granny Smith (about 2 medium))
• ¾ cup old fashioned rolled oats
• ⅓ cup lightly packed brown sugar (light or dark)
• ½ teaspoon ground cinnamon
• ¼ teaspoon salt
• 2 tablespoons unsalted butter (melted)
• ¼ cup roughly chopped walnuts
• ¾ cup powdered sugar
• 2 tablespoons milk (or cream for a richer glaze)
• ½ teaspoon vanilla extract