Mix flour, baking powder, salt, and sugar in a large bowl.
In another bowl, whisk together the milk, butter, and vanilla.
Add the milk mixture to the flour mixture, and stir until the batter is combined.
Add the banana and blueberries; gently fold to combine.
Heat a large non-stick griddle or skillet over medium heat, and grease lightly with non-stick spray.
Pour 1/2 cup 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 eggs are done.)
In the meantime, in a non-stick pan over medium heat, brown the chicken sausage on both sides.
Lightly grease a non-stick pan over medium heat with non-stick spray. Crack the eggs in the pan. Cook the eggs till the whites are mostly firm for about 2 to 3 minutes, and gently flip the eggs with a spatula and cook for 30 seconds more. Season with salt and pepper.
Use butter and maple syrup (if desired) on the pancakes and serve with chicken sausage and eggs.