Stir the Greek yogurt, vanilla protein powder (if using) and the vanilla extract in a small bowl until smooth and slightly aerated. Taste and adjust sweetness if desired.
Warm a small nonstick skillet over medium heat. Add the coconut oil or butter and let it melt, swirling to coat the pan.
Combine the maple syrup and cinnamon in a small cup. Add the banana slices to the skillet in a single layer and spoon the syrup mixture over them. Cook 1.5–2 minutes without moving until the undersides are glossy and browned.
Gently flip the banana slices and cook another 1–1.5 minutes until both sides have golden caramelized spots. Tilt the pan and spoon the pan juices over the bananas once or twice so they glaze.
Transfer the warm bananas to a plate and, in the same skillet, toss the chopped nuts for about 30–45 seconds until fragrant and lightly toasted. Remove from the heat and let the nuts cool for 20–30 seconds so they crisp up.
Spoon the yogurt into a serving bowl. Arrange the caramelized banana slices on top, sprinkle with the toasted nuts, and finish with a thin drizzle of almond butter. Scatter a pinch of flaky sea salt over everything to heighten the flavors.