Preheat oven to 350 degrees Fahrenheit Whisk together oats and cinnamon in a medium or large bowl. Set aside.
In a small bowl, mix in banana, honey, melted butter and vanilla. Create a well in the oats mixture and pour in banana mixture. Using a wooden spoon or spatula, incorporate ingredients together.
Divide mixture into 8 muffin tins. Using your fingers or a small spoon, mold mixture into the shape of the muffin tin, creating a well in the middle (this will be where the yogurt will go later!) Make sure to cover any gaps so that the yogurt doesn't spill out afterwards. Cover and refrigerate for 30 minutes or up to an hour.
Bake for 15 minutes or until the sides look golden brown and well set. I'd recommend setting a timer for 12 minutes and checking from that point onwards, depending on the heat of your oven, and how thick your granola cups are! The thicker it is, the longer it will take to bake!
Remove from oven and let cool for 10-15 minutes. Using a sharp knife, gently loosen edges of cups and remove from tray. Top with 1 tbsp greek yogurt and some fruit. Serve immediately
Notes
You can make the granola cups 1-2 days ahead of time and store in a closed container.