
½ cup old-fashioned or quick-cooking rolled oats
¼ cup all-purpose flour
¼ cup granulated sugar
¼ cup packed dark brown sugar
1 teaspoon ground cinnamon
¼ teaspoon ground nutmeg
⅛ teaspoon salt
⅓ cup salted butter, melted
1 tablespoon salted butter, softened
2 cups all-purpose flour
2 teaspoons baking powder
½ cup cold salted butter, cut up
⅔ cup granulated sugar
½ teaspoon ground cinnamon
¼ teaspoon ground nutmeg
¼ teaspoon ground allspice
1 large egg, at room temperature
½ cup milk
1 teaspoon pure vanilla extract
1 large Granny Smith or Gala apple, cored, peeled and sliced thinly (about 1 cup)
1 teaspoon fresh lemon juice
1 tablespoon salted butter, melted
Vanilla bean ice cream, for serving
Homemade Caramel Sauce, for serving