Preheat oven to 350 degrees and line a bread loaf pan with parchment paper.
Combine the dry ingredients for the bread (whole wheat pastry flour through nutmeg in a large bowl.
Whisk together all remaining ingredients (except the apples) in a medium bowl.
Pour the wet into the dry ingredients and mix until mostly combined.
Add the apples and fold in until thoroughly combined.
Pour the batter into the pan.
Combine the streusel ingredients in a small bowl and incorporate them into a "crumble" using your fingers.
Sprinkle the streusel on top of the bread and bake for about 40 minutes.
Remove the bread from the oven and let cool.
Combine the icing ingredients in a small bowl and microwave for about 15 seconds to warm it up. Mix with a spoon until it reaches an "icing" consistency.