Apple Cinnamon-Raisin & Walnut Baked Oatmeal

INGREDIENTS

• 2 cups old-fashioned rolled oats (do not substitute quick oats)
• ½ cup walnuts, toasted and coarsely chopped, divided
• 1½ teaspoons ground cinnamon
• 1 teaspoon baking powder
• ½ teaspoon fine sea salt
• 2 cups low-fat milk (anything from skim to 2%)
• ⅓ cup pure maple syrup
• 1 egg
• 3 tablespoons unsalted butter, melted, divided
• 2 teaspoons vanilla extract
• 2 Gala apples, peeled, cored and cut crosswise into ½-inch pieces
• 1½ cups raisins, divided