Line your slow cooker with parchment paper, leaving enough overhang to lift the bread out later.
In a large bowl, mix together mashed bananas, eggs, melted coconut oil, and vanilla extract until well combined.
In a separate bowl, whisk together almond flour, baking soda, cinnamon, and salt.
Add the dry ingredients to the wet ingredients and stir until just combined, then fold in the chopped walnuts.
Pour the batter into the prepared slow cooker, spreading it evenly.
Place a clean kitchen towel under the lid to absorb moisture, then cook on high for 3-4 hours until a toothpick inserted in the center comes out clean.
Use the parchment paper to lift the bread out of the slow cooker and let cool on a wire rack before slicing.