Line baking sheet with parchment paper. In a skillet, toast fennel seeds over moderate heat until fragrant. Add sugar and cook until melted and covers seeds. Scrape candied fennel seeds onto a plate and cool.
Put chocolate in a microwave-safe bowl and microwave in 30-second intervals until almost melted.
Working very quickly, dip wafers in chocolate and transfer to baking sheet. Sprinkle with fennel seeds, ginger and sea salt. Refrigerate until set, about 5 minutes, then serve.