Preheat oven to 400 degrees
CRUMBLE
Add 3 tbsp melted butter, oats, cinnamon and flour together in a small bowl and mix with a fork until a crumble forms
Place crumble in the freezer for 15 minutes
In a large bowl, whisk together flour, baking powder, baking soda, salt, cinnamon, and nutmeg.
In another bowl, mix avacado oil, maple syrup, eggs, and vanilla extract until well combined.
Pour the wet ingredients into the dry ingredients and stir until just combined. Be careful not to overmix. Let the batter rest 15-20 minutes
Gently fold in the carrots
Divide the batter evenly and fill to the top
Generously sprinkle crumble over the top of muffins and then pour 1 tbsp of melted butter over the top of the crumble
Bake at 400 degrees for 5 minutes, and then reduce heat to 375, and bake until a toothpick inserted into the center of a muffin comes out clean, and the top has gotten crunchy
Allow the muffins to cool in the pan for 10 minutes before transferring them to a wire rack to cool completely.