In a mixing bowl, combine Greek yogurt, honey or maple syrup, and vanilla extract until smooth.

Gently fold in the dark chocolate chips and fresh raspberries into the yogurt mixture.

Line a baking sheet with parchment paper and spoon the yogurt mixture onto it, spreading into an even layer about half an inch thick.

Sprinkle crushed nuts and chia seeds over the top, if desired.

Transfer to the freezer and chill for at least 2 hours until firm.

Remove from the freezer, let sit for 5 minutes, and then break into pieces to serve.