For the chicken sausage: If raw, cook in a 400°F oven to an internal temperature of 160°F using a thermometer. If already cooked: Preheat a non-stick pan over medium heat and brown the chicken sausage slices on each side.
Mix flour, baking powder, salt, brown sugar, and cinnamon in a large bowl. Whisk in the milk and vanilla until the batter is combined. Gently fold in the chopped banana.
Heat a large non-stick griddle or skillet over medium heat and grease with butter as needed.
Pour 1/3 cup of batter into circles.
Flip once bubbles appear on top and the bottom is golden brown. Cook until firm and golden brown on both sides. (Keep pancakes warm in a 200°F oven until all are done if desired.)
Once all of the pancakes are done toast the walnuts in the remaining butter in the pan.
Top the pancakes with sliced banana, syrup, and raspberries. Serve with chicken sausage.