Gluten-free Crumb Cake Muffins

-1 Preheat the oven to 350 F
-1 In a large bowl, combine the coconut sugar, yogurt, cinnamon, oil, eggs and vanilla and whisk together until smooth.
-1 Add in the oat flour, salt, baking soda and baking powder and mix well.
-1 Line a muffin tin with cupcake liners and divide the batter evenly into about 10 liners.
-1 To make the crumb topping, mix together the oat flour, cinnamon and sugar in a small bowl. Add in the cold butter and work the flour mixture into the butter using your hands to break up the butter and form crumbs.
-1 Sprinkle the crumbs over each muffin. Bake for about 18 minutes, until the tops are firm to touch
-1 Let them muffins cool and dust them with powdered sugar. Keep refrigerated for up to 2 weeks, or keep at room temperature for up to 3 days.