Preheat the oven to 350°F. Lightly grease a 9" x 13" pan.
To make the bars: Beat the butter and sugar in a medium bowl. Beat in the egg, then scrape the sides and bottom of the bowl. Beat in the applesauce, boiled cider or apple juice concentrate, baking powder, salt, and spices. The mixture will look curdled.
Stir in the oats and flour, mixing thoroughly. Fold in the apples. Spoon the batter into the prepared pan.
Bake the bars for 35 to 40 minutes, until their center is moist but not liquid. Remove them from the oven and let them cool completely before spreading with the glaze.
To make the glaze: Heat the peanut butter and honey together until the peanut butter softens. Stir the mixture until smooth, and spread on the cooled bars.
Tips from our Bakers
These whole-grain bars, made with both whole wheat flour and oats, can be a bit crumbly and delicate. For sturdier bars, ones more amenable to transporting to a potluck or bake sale, omit the oats; and use 1 1/2 cups (180g) unbleached all-purpose flour in place of the whole wheat flour.
For convenience's sake, feel free to substitute 1 tablespoon Apple Pie Spice for the cinnamon, nutmeg, ginger, and allspice listed in the recipe.
For a milder, less peanut-ty glaze, try the following: Mix 1/2 cup (135g) peanut butter with 1/4 cup (84g) honey. Stir in 1 cup (114g) confectioners' sugar and 1/8 teaspoon salt. Add 2 1/2 to 3 tablespoons milk, enough to make a spreadable glaze. Spread a thin layer all over the bars.