Position a rack in the center of the oven and preheat to 350°F. Grease a 9x5-inch loaf pan and line it with parchment, leaving a slight overhang to lift the loaf out later.
In a medium bowl whisk together the flour, baking soda, salt, and cinnamon until evenly combined. Set the dry mix aside.
In a large bowl, beat the softened butter with both sugars until pale and slightly fluffy, about 2 minutes with an electric mixer or several minutes by hand. This creates a lighter crumb than using melted butter.
Add the mashed bananas to the butter-sugar mix, then beat in the eggs one at a time until incorporated. Stir in the yogurt and vanilla until the batter is smooth.
Fold the dry ingredients into the wet mixture with a rubber spatula — mix just until you no longer see streaks of flour. Gently fold in the mini chocolate chips, reserving a couple tablespoons for the top.
Spoon the batter into the prepared pan, smoothing the top. Scatter the reserved chips over the loaf and press them lightly into the surface.
Bake at 350°F for 55–65 minutes, or until a toothpick inserted near the center comes out with a few moist crumbs (avoid a wet batter smear). If the top is browning too fast after 40 minutes, tent with foil.
Let the loaf cool in the pan on a wire rack for 15 minutes, then use the parchment overhang to lift it out and cool completely before slicing. Cooling fully gives a neater slice and better texture.