Preheat the oven to 350ºF. Spray a 7x11 (or similar size) casserole dish lightly with non-stick spray and set aside.

In a large bowl, toss together the bread cubes and chopped pecans (reserve a couple Tablespoons or so for sprinkling on top, if desired). Set aside.

In a medium size bowl, whisk together the Greek yogurt, milk, the 2 mashed bananas, brown sugar, eggs, cinnamon, vanilla extract, and salt until completely combined. Pour mixture over bread cubes and stir gently until all of the bread is covered.

Pour coated bread into prepared dish and top with reserved chopped pecans (if you saved them) and banana slices. Bake for 33-35 minutes until top and edges just start to brown or until a toothpick inserted in the center comes out clean. Allow to cool at least 15 minutes before serving, or cool completely and chill in the refrigerator to serve cold. Dust with powdered sugar, if desired. Leftovers can be stored in the refrigerator, covered tightly, up to 5 days. To serve warm leftovers, reheat individual servings in the microwave.