Preheat your oven to 350°F (175°C) and line a 12-cup muffin tin with paper liners or lightly grease with cooking spray. Position your oven rack in the center position for the most even baking.
In a large bowl, whisk together the whole wheat flour, baking soda, salt, cinnamon, nutmeg, and ginger until well combined.
In a separate medium bowl, whisk together the pumpkin puree, honey or maple syrup, melted coconut oil, almond milk, egg, and vanilla extract until smooth.
Pour the wet ingredients into the dry ingredients and gently fold together with a rubber spatula until just combined. Stop mixing as soon as no dry flour remains visible.
Gently fold in the blueberries, being careful not to crush them. If using fresh berries, try tossing them with 1 teaspoon of flour first to prevent them from sinking.
If making the optional streusel topping, combine the oats, flour, brown sugar, and cinnamon in a small bowl. Cut in the cold butter using a fork or your fingertips until the mixture resembles coarse crumbs.
Divide the batter evenly among the prepared muffin cups, filling each about ¾ full. If using the streusel, sprinkle it evenly over the tops of the muffins.
Bake for 20-22 minutes, or until a toothpick inserted into the center comes out clean or with just a few moist crumbs. Avoid opening the oven door during the first 15 minutes of baking.
Allow the muffins to cool in the pan for 5 minutes before transferring to a wire rack to cool completely.