Line a large baking sheet with parchment paper and set aside.

Place chopped dark chocolate in a microwave-safe bowl. Microwave at 50% power in 30-second intervals, stirring after each, until melted and smooth with just a few unmelted pieces remaining. Stir until completely smooth.

If using vanilla extract, stir it into the melted dark chocolate until evenly combined.

Pour the melted dark chocolate onto the prepared baking sheet and spread into an even rectangle about 1/4-inch thick using an offset spatula.

Melt the white chocolate using the same method as the dark chocolate, stirring until completely smooth.

Drizzle the melted white chocolate over the dark chocolate base in random lines and dollops. Use a toothpick or skewer to create swirls by dragging through both chocolates in figure-eight or S-shaped patterns.

Crush about half of the freeze-dried strawberries into smaller pieces and leave the rest whole. Immediately sprinkle all the strawberries over the chocolate while it's still wet, pressing down gently so they stick.

If desired, finish with a light sprinkle of flaky sea salt. Refrigerate for 20-25 minutes until completely firm and set.

Once hardened, break the bark into irregular pieces by hand. Store in an airtight container with parchment between layers.