Preheat the oven to 350°F. Lightly oil or butter a 9" glass pie plate or an 8x8" glass baking dish. Combine the cinnamon filling ingredients in a small bowl, stir and set aside.
In a large mixing bowl, cream together the melted butter and coconut sugar. Add the eggs and stir until thoroughly combined.
Add the cassava flour, baking powder, baking soda, sea salt, and cinnamon. Add the yogurt last and stir until the batter is smooth.
Spread half of the batter into the pie plate (or baking dish). Sprinkle the cinnamon sugar filling evenly over the batter. Spread the remaning coffee cake batter on top.
In a food processor, combine the cassava flour, sugar, and cold butter for the crumble topping. Cut the butter into tablespoon size chunks before adding it to the food processor.
Pulse until big crumble form. First the crumble will seem loose and only small crumbles will form. Keep pulsing until the butter softens enough to create large crumbles.
Spread the crumble topping evenly over the coffee cake. Place the coffee cake on a baking sheet to catch any spills when the crumble topping bakes down (which I have not had happen).
Bake for 40-45 minutes. A toothpick inserted into the center of the coffee cake should come out with only a few dry crumbs. Let the coffee cake cool for 10-15 minutes before slicing and serving. Cool completely before storing leftovers.