In a mixing bowl, combine the dairy-free yogurt, maple syrup (if using), and vanilla extract. Stir until well blended.
Line a muffin tin with paper liners or silicone molds.
Spoon a layer of the yogurt mixture into each cup, filling them about halfway.
Add a layer of mixed berries and banana slices on top of the yogurt in each cup.
Top each cup with more yogurt mixture until nearly full, leaving a little space at the top.
Sprinkle granola on top of each cup for added crunch.
Freeze the cups for at least 4 hours or until completely solid.
To serve, remove the cups from the muffin tin and peel off the liners. Garnish with fresh mint leaves if desired.