1. Coat 2 large muffin tins (6 muffin cups per tin) with cooking spray or place parchment baking cups (cupcake liners) inside the each cup within the pan, and set aside.
2. In a medium size bowl, combine the flour, oats, sugar, baking powder, baking soda, and salt.
3. In a second bowl, combine the butter, Greek yogurt, honey, eggs, buttermilk, and vanilla.
4. Pour the wet mixture into the dry mixture and stir to combine well.
5. Very gently pour in and fold in the blueberries.*the mixture should be very thick but if it's too thick, or dry and crumbly, add some more buttermilk until it mixes well.
6. Spoon the mixture into the muffin tins *I used a 1/3 measuring cup*
7. Let the muffins rest for 1 hour in the lined muffin tins on the counter.
8. While the muffins are resting you can make the optional cinnamon crumble topping *see note below* Once the muffins have rested at least a hourm, and you have placed the crumble on top of each muffin, proceed to Preheat the oven to 400F.
9. Bake for 5-7 minutes on 400F and then drop the temperature to 350F and bake for the remaining time. (Bake until the tops of the muffins are golden in color, about 20-25 minutes total baking time.

Note:

HOW TO MAKE CINNAMON CRUMBLE TOPPING:

While the batter is resting for an hour. In a medium bowl, combine the flour, brown sugar, cinnamon and nutmeg. Toss the ingredients together until they’re well combined. Next, pour in the melted butter. Using your fingers, work the melted butter into the dry ingredients, until fine crumbs form and no dry flour is remaining. Spoon a few tablespoons of crumble over each muffin. If you are not a fan of crumble, you can disregard this part.