In a mixing bowl, combine creamy peanut butter and honey until smooth; stir in a pinch of sea salt and fold in crushed granola.

In a separate bowl, whisk together Greek yogurt and vanilla extract until luxuriously smooth.

Line a muffin tin with paper liners, then press the peanut butter-granola mixture into the bottom of each liner.

Add the yogurt mixture over the granola base in each muffin liner, filling them about three-quarters full.

Top each yogurt layer with fresh berries and chopped walnuts, and drizzle with honey if desired.

Place the muffin tin in the freezer for 30 to 60 minutes, or until solid.

Let the muffin tin sit at room temperature for 2-3 minutes before removing the bites from the liners.