Peel and chop sweet potatoes into 1-inch thick cubes.  Add potatoes to a pot of cold water and bring to a boil.  Boil sweet potatoes until fork tender (approx. 25-30 minutes).

While potatoes are boiling, preheat oven to 375 degrees F and spray an oven-safe dish with cooking spray.  I used a 10" x 2" tart pan.

Meanwhile, in a small bowl, combine the oats, flour, chopped pecans, brown sugar, cinnamon and salt.  Add in your softened butter, using your hands to completely incorporate it with the dry ingredients.

Drain potatoes and add to a large bowl.  Add milk, butter, brown sugar (or maple syrup) and salt.  Using a potato masher, mash and mix the potatoes and other ingredients until smooth and combined.  Spread evenly into your prepared baking pan.

Finally, sprinkle your crumble mixture evenly over the top of the sweet potatoes.

Bake for 20-25 minutes, or until nuts and oats are golden brown.