Preheat the oven to 350 degrees F. Line a muffin tray with 9 paper liners or silicone muffin cups. Alternatively, you can grease a muffin tin with non-stick cooking spray or coconut oil. This is an important step as this will help you get the granola cups out much more easily. In a large bowl, mash the banana, then add the peanut butter, maple syrup, and vanilla. Stir to combine, then add in the oats, cinnamon and salt. Mix until combined (it helps if you use your hands). Allow mixture to sit for 5 minutes.
Divide the granola mixture evenly between the 9 muffin holes.
Next, use the back of a tablespoon to shape the granola mixture into little cups, forming a hollow center. It helps if you wet the back of the spoon with a bit of water to prevent the mixture from sticking to the spoon.
Bake the granola cups in the oven for 18-20 minutes.
Allow the cups to cool for at least 30 minutes before removing them from the muffin pan. Otherwise, they might fall apart.
When they're ready to be removed from the muffin pan, carefully pop them out of the liners or silicone cups or gently slide a paring knife along the edges of the cups, to loosen them from the muffin tin.
Fill them with yogurt and top with mixed berries or other desired fruit. Serve and enjoy!