Preheat your oven to 375°F. Line a muffin tin with liners or lightly grease with baking spray.
In a medium size bowl, cut your butter into chunks and melt in the microwave. Set the butter aside to cool.
In a medium bowl, add flour, oats, cinnamon, salt, baking powder, and baking soda and whisk together. Set aside.
In a large bowl, add your brown sugar and oil and mix.
Add in your eggs and mix together until the eggs have become homogenous with the sugar and oil.
Add in your buttermilk, maple and vanilla extracts and mix together.
Add your dry ingredients to the wet and stir until just combined. Do not over mix.
Scoop your muffins into your muffin tin, about ¼ cup into each liner.
Add your salt and maple to your melted butter then mix.
Add granulated sugar, brown sugar, cinnamon and flour and mix until the mixture becomes clumpy.
Spoon the crumble on top of the muffins, covering the tops generously.
Bake your muffins on the center rack of your oven for 20 minutes. The edges of the muffins will be golden brown. Carefully remove the muffins from the muffin tin and onto a cooling rack.
Allow your muffins to cool for at least 20 minutes before consuming. Store in an airtight container for up to 3 days. Enjoy!
