In a medium bowl, stir together the Greek yogurt, honey, vanilla extract, and cinnamon (if using) until smooth and well combined.
Lightly crush 1/2 cup of the blueberries with a fork in a small bowl to release their juices, creating a jammy texture. Leave the remaining 1 cup of blueberries whole.
In clear glasses or mason jars, create layers by starting with 2-3 tablespoons of the yogurt mixture at the bottom of each glass.
Add a layer of crushed blueberries (about 1 tablespoon per glass), followed by a few whole blueberries.
Sprinkle a layer of granola over the blueberries, using about 2 tablespoons per glass.
Repeat the layering process one more time: yogurt, crushed blueberries, whole blueberries, and granola, ending with a final dollop of yogurt on top.
Finish each parfait with remaining whole blueberries, sliced almonds, and a light drizzle of honey. Garnish with fresh mint leaves if desired.
Serve immediately for maximum crunch, or refrigerate for up to 2 hours before serving. If making further ahead, add the granola layer just 30 minutes before serving.