Preheat the oven to 350 degrees F. Grease an 8x8 baking pan and line with parchment paper.
In a large mixing bowl, stir together flour, coconut sugar, baking soda, and sea salt.
Add almond milk, coconut oil, vanilla extract, and apple cider vinegar. Stir until combined.
Pour half of the batter into the prepared pan and spread in an even layer with a spoon or a spatula.
In a separate bowl, stir together ingredients for the filling. Sprinkle over the cake batter in the pan evenly, then spread the remaining half of the batter on top.
In a separate bowl, stir together ingredients for the crumb topping until a crumbly mixture is formed. Sprinkle this mixture over the cake batter.
Bake for 40-45 minutes, until a toothpick inserted in the center comes out clean.
Cool for 10 minutes, then removefrom the pan carefully using the parchment paper. Cool completely.
Slice into 16 squares, and enjoy!