Place butter in freezer for 30 minutes before starting.
Grate butter using a box grater and place back in the freezer for 10 minutes.
Preheat oven to 375 F and spray a 9" cake pan generously with cooking spray.
In a medium bowl, combine almond flour, granular erythritol, and salt.
Add butter and mix until butter is well coated.
Remove one cup of the butter/flour combo and place it in the fridge.
Add baking powder, psyllium husk, heavy cream, vanilla, and eggs.
Combine using an electric mixer until batter is completely smooth.
Pour smooth mixture into the prepared cake pan.
Add cinnamon and chopped pecans to the flour combo we set aside, and toss until well combined.
Sprinkle the crumbs over the top of the cake, pressing lightly with your hands so the crumbs adhere.
Bake in preheated oven for 35 minutes.
Remove from oven, and cover the cake in foil (this will prevent the top from burning).
Return to the oven and bake for another 45 minutes.
Allow cake to cool completely in the pan before removing it. Enjoy!