Preheat oven to 350°F (175°C). Grease a 9x5-inch loaf pan or line with parchment paper.
Whisk together melted butter and brown sugar. Add eggs, mashed bananas, and vanilla.
Sift flour, baking soda, salt, and cinnamon. Fold into the wet ingredients, being careful not to overmix.
Stir in Greek yogurt for a rich, bakery-style texture.
Pour batter into the pan and smooth the top.
Bake for 50-55 minutes or until a toothpick comes out clean.
Cool for 10 minutes, then transfer to a wire rack. Slice and enjoy!