Preheat oven to 350F.
Start by making your streusel topping in a medium size bowl. Mix all your ingredients and then place in the fridge for 15 minutes.
Meanwhile, whisk your dry ingredients in a large bowl: flour, sugar, baking powder, baking soda, salt, and cinnamon.
Add in your wet ingredients to dry: coconut oil, non-dairy milk, vanilla, and sour cream. Stir until combined.
Make your cinnamon sugar layer in a small bowl by mixing brown sugar with cinnamon.
Line your muffin pan with cupcake liners. Begin spooning batter into your muffin tin until it's only half full.
Spoon ~1-2 teaspoon of brown sugar cinnamon mix on top of batter and spread an even layer.
Top the sugar cinnamon mix with more batter.
Sprinkle on your chilled streusel topping (Be generous with the topping- This is one of the best parts of the muffin!)
Bake for 16-18 min until toothpick comes out clean.
To make optional icing just mix together powdered sugar and milk. Drizzle over your cooled muffin before eating.
Enjoy!