Make the raspberry jam:

Line a large baking sheet with parchment paper.

Place the raspberries and chia seeds in a large bowl. Using a fork, mash the raspberries until the mixture becomes jammy. If using frozen raspberries, add 1/4 cup water, one tablespoon at a time, until the berries loosen up.

Scoop the jam mixture by heaping tablespoonfuls onto the prepared baking sheet. Freeze for at least 1 hour or up to 8 hours.

Melt the chocolate:

Line another baking sheet with parchment paper.

Microwave the dark chocolate in a medium microwave-safe bowl on Medium for 1 minute. Stir and continue microwaving in 20-second intervals, stirring after each interval, until the chocolate is fully melted. Alternatively, you can melt the chocolate using a double boiler by placing the chocolate in the top bowl over hot water and stirring until smooth.

Coat the raspberry bites with chocolate:

Once the raspberry bites are frozen, remove them from the freezer.

Using a fork, hold each raspberry bite over the melted chocolate and spoon the chocolate onto it, allowing any excess to drip back into the bowl. Spoon about 1 teaspoon of melted chocolate onto the parchment paper, and then place the coated raspberry bite on top. Repeat this process with all the bites.

Drizzle with extra chocolate (optional):

If desired, drizzle the remaining melted chocolate over the tops of the bites for an extra chocolatey finish.

Serve and store:

Serve immediately, or store the bites in an airtight container in the freezer for up to 1 month.