Start by making the crumble: in a small bowl, add the chopped pecans, pure maple sugar and ghee and mix with your fingers until well distributed. Set aside.
Grease a loaf pan really well with ghee or coconut oil and, for extra protection against sticking, line the bottom with a rectangle of parchment paper cut to the exact size of the pan and set aside.
In the bowl of your food processor, place all the dry ingredients and then give them a good spin until they are evenly combined and all the lumps have been destroyed, about 30 seconds. Transfer to a bowl and set aside.
In that same bowl of that same food processor, add the sweet potato flesh, ghee and maple syrup and process until well combined and creamy. Add the eggs and resume processing until the ingredients are homogeneously combined and creamy.
Add the reserved dry ingredients to this wet mixture and again, process until well combined, no more.
In a glass measuring cup, mix the buttermilk, lime juice and vanilla extract. Add that to the cake batter and process for about 15 seconds, or until combined.
Transfer this batter to a large mixing bowl (the one you used earlier for the flour should work just fine) and delicately stir in the grated apples.
Pour the finished batter into the prepared loaf pan and sprinkle the reserved crumble all over the top. Place the bread in the oven and bake for about 50 minutes, or until the top is nicely golden and the center is fully set (a toothpick inserted in the middle of the loaf should come out clean).
Set the loaf on a wire rack and let it cool in the pan for about 10 minutes before very delicately unmolding it.
Finish cooling on the rack and transfer to the refrigerator to chill completely before slicing.
This bread will keep for up to a week in an airtight container.
Notes
*To bake the sweet potato, cut it in half then wrap it in foil and bake it in a 375°F oven for about 35-40 minutes or until soft. Allow to cool completely and then remove the peel. It might be a good idea to do that a day ahead of time. And make some extra: leftover baked sweet potatoes are always a good thing to have in the fridge...