Preheat your oven to 350°F (175°C). Grease a 9-inch round cake pan.
Combine dry ingredients: In a large mixing bowl, whisk together 1/2 cup coconut flour, 1/4 cup tapioca flour, 1/2 cup granulated sugar, 1/4 cup brown sugar, 1/2 tsp baking soda, 1/4 tsp salt, and 1/2 tsp cinnamon.
Mix wet ingredients: In a medium bowl, whisk together 1/2 cup melted coconut oil, 4 large eggs, 1/2 cup coconut milk, and 1 tsp vanilla extract until smooth.
Combine: Pour the wet ingredients into the dry ingredients. Stir with a spatula until just combined. For an extra touch, fold in 1/4 cup shredded coconut if desired.
Transfer to pan: Pour the batter into the greased cake pan, smoothing the top with your spatula.
Bake: Place in the preheated oven and bake for 30 minutes, or until a toothpick inserted into the center comes out clean.
Cool and enjoy: Let the cake cool in the pan for 10 minutes before transferring to a wire rack to cool completely. Slice and savor with your favorite coffee.