Melt dark chocolate in a microwave-safe bowl in 15-second intervals, stirring after each melting, 1 to 3 minutes.
Melt white chocolate in a separate microwave-safe bowl in 15-second intervals, stirring after each melting, 1 to 3 minutes.
Line a baking tray with baking parchment. Pour dark chocolate on the paper; spread into a large rectangle. Drizzle white chocolate over the dark chocolate in lines and zigzags. Swirl chocolates together into a marble pattern using a skewer.
Scatter heart-shaped sweets over chocolate. Scatter freeze-dried strawberries and pink sprinkles in the remaining gaps. Let stand at room temperature for about 20 minutes.
Refrigerate chocolate bark until firm, about 30 minutes. Break into large chunks.