Preheat oven to 350 degrees F (177 degrees C). Brush an 8 x 8 inch baking pan with oil. Cut a piece of parchment paper the width of the bottom of the pan and long enough to overlap the two sides of the pan. Brush parchment paper with oil, set aside.
To make crumb topping, add chopped pecans, almond flour, powdered stevia, salt, cinnamon, and melted coconut oil in a medium bowl. Stir to combine, chill.
For the cake, add almond flour, coconut flour, salt, baking soda, and ½ Tbsp cinnamon in a large bowl, whisk to combine, set aside.
In a small bowl, add eggs, powdered stevia, 1 Tbsp cinnamon, and whisk until frothy. Add yogurt, stir to combine.
Add liquid ingredients to dry ingredients, stir to thoroughly combine. Spoon cake batter into prepared pan, then evenly sprinkle with crumb topping.
Bake crumb cake for 20 minutes or until center is firm to the touch. Cool, and serve!