Preheat your oven to 375°F (190°C). Line a muffin tin with paper liners.
In a large bowl, whisk together the flour, sugar, baking powder, and salt.
In another bowl, mix the almond milk, vegetable oil, and vanilla extract.
Pour the wet ingredients into the dry ingredients and stir until just combined.
In a small bowl, combine the brown sugar, flour, and cinnamon for the streusel topping. Stir in the melted vegan butter until the mixture is crumbly.
Fill the muffin cups about ⅔ full with the batter. Sprinkle the streusel topping evenly over each muffin.
Bake for 20 minutes or until a toothpick inserted into the center comes out clean.
Let the muffins cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.