Add melted butter and granulated sugar to a large bowl and cream together using a large whisk or with a hand or stand mixer until well combined.
Whisk in eggs, vanilla extract, mashed ripe bananas, tahini, and milk until smooth.
Whisk in salt and ground cinnamon and make sure they're well incorporated.
Using a large spoon, fold in rolled oats until well combined.
Line an 8-cup muffin tin with liners or butter and flour cups. Spoon mixture equally into cups and bake for approximately 45 minutes or until top is set and a light golden brown.