Line a rimmed baking sheet with parchment paper. Clear a level space in the freezer so the tray can sit flat.

Stir Greek yogurt, honey and vanilla in a bowl until evenly blended. Taste before freezing and adjust sweetness if desired.

Spread into a roughly 9-by-12-inch rectangle about 1/4 inch thick on the parchment. Scatter strawberries and blueberries evenly and gently press them into the yogurt.

Freeze flat until completely firm, about 4 hours; timing varies by freezer and thickness.

Lift the parchment, break into 8 portions and serve straight from the freezer. Store remaining pieces immediately in an airtight freezer container with parchment between layers. For best texture, use within 2 weeks.