Preheat the oven to 400°F (200°C). Grease a 12-cup muffin tin or line with paper liners and set aside.
In a large bowl, whisk together the all-purpose flour, whole wheat flour, dark brown sugar, baking powder, salt, and 1 teaspoon ground cinnamon until evenly combined.
In a separate bowl, whisk the applesauce, 4 oz almond milk, olive oil, and maple syrup until smooth.
Pour the wet ingredients into the dry ingredients and stir gently until just combined; do not overmix.
Divide the batter among the prepared muffin cups, filling each about two-thirds full.
Sprinkle a little of the cinnamon-sugar mixture (2 tablespoons sugar mixed with 1 teaspoon cinnamon) over each muffin.
Bake for 18–20 minutes, until a toothpick inserted into the center comes out clean.
Let the muffins cool in the pan for at least 20 minutes, then transfer to a cooling rack to cool completely.
Make the glaze by whisking the confectioners' sugar with 2 teaspoons almond milk, adding a little more milk if needed to reach a drizzleable consistency.
Drizzle the glaze over cooled muffins.