Apple Buckwheat Crumble Cake

Name: Apple Buckwheat Crumble Cake
Ingredients: For the cake:; 2 cups pecans, (200gm); 1/2 cup butter or coconut oil; 1/2 cup honey; 4 large eggs; 1/2 cup applesauce; 2/3 cup buckwheat flour; 1/2 cup cornstarch or arrowroot starch; 2 teaspoons baking powder; 1 tablespoon ground chia seeds; 2 teaspoons cinnamon; 2 cups grated apple, with peel, loosely packed; For the crumble topping:; 1/4 cup butter or coconut oil; 1/4 cup sugar; 1/2 cup buckwheat flour; 1/4 cup quick oats; 1/4 teaspoon cinnamon; 2 tablespoons sesame seeds (optional)