Preheat the oven to 350°F (175°C) and grease the cake pan.
Mash the bananas in a bowl until smooth.
Mix melted coconut oil, brown sugar, and vanilla into the mashed bananas.
Combine flour, baking powder, baking soda, and salt in a separate bowl.
Add dry ingredients to the wet mixture, alternating with almond milk, and stir until just combined.
For the crumb topping, mix flour, brown sugar, cinnamon, and solid coconut oil until crumbly.
Pour batter into the prepared pan and sprinkle the crumb topping evenly.
Bake for 35 minutes, or until a toothpick comes out clean.
Let the cake cool for 10 minutes before slicing and serving.