Cut your ripe banana into 1-inch pieces and place them at the bottom of your blender. This helps it blend more evenly and quickly.
Pour in the milk, vanilla extract, ground cinnamon, and lemon juice. These ingredients enhance the banana flavor and balance the sweetness.
Scoop in the vanilla ice cream on top of the liquid mixture. This prevents the ice cream from sticking to the blender blades.
Blend everything on high speed until the mixture is completely smooth and creamy. If the shake is too thick or seizes up due to cold ingredients, add small splashes of milk to loosen it.
Divide the milkshake between two glasses. For a little extra flair, top with whipped cream and a light sprinkle of cinnamon before serving.