Preheat oven to 425F.
Line a muffin tin with paper liners.
Place peeled bananas in a high powered blender or food processor (only if it’s liquid sealed), and blend until smooth.
Add canola oil and melted butter and blend again.
Dump in granulated sugar and brown sugar, blend again.
Add eggs, vanilla, and milk and blend until incorporated.
In a medium bowl, combine the flour, cardamom, baking powder, baking soda, and salt. Whisk to combine.
Add dry ingredients to the wet mixture and pulse until just combined.
Add walnuts, and quick pulse 2-3 times, until the walnuts are chopped and incorporated.
Using a medium cookie scoop, fill the muffin liners. The liners should be between half and three quarters full