Stir the yogurt with 1 teaspoon vanilla sugar and a small pinch of salt. Whisk briefly until smooth and slightly lighter in texture. Spoon into a serving bowl.
Cut the banana into thick slices, about 1–1.5 cm thick.
Place the banana slices in a dry frying pan over medium heat. Sprinkle with cinnamon (as much as you like) and the remaining vanilla sugar. Cook for 2–3 minutes on each side until golden and soft. Add a small squeeze of lemon at the end if using.
Spoon the warm banana over the yogurt. Top with blueberries and chopped walnuts. Serve immediately.