Melt the coconut oil and mix it with the maple syrup in a large bowl.
Add the eggs and beat well. Mash in the bananas.
Mix in the flour, salt, cinnamon and vanilla bean paste and stir until well combined.
Add the blueberries and stir through.
Lightly spray your slow cooker pot with oil to prevent sticking. Place a large cake case in the pot and spoon the mixture into the case (I sometimes double the cake cases so they are easier to pull out).
Replace the lid, add a tea towel or some squares of kitchen roll under the lid to catch drips, and cook on high for approx 1.5 to 2 hours, until firm in the centre and brown around the edges.
Use the edge of the cake case to pull the cake out of the slow cooker pot and leave it to cool.