Start by melting the chocolate to packaging instruction, being careful not to burn the chocolate. You do not want it to be really hot, just completely melted and smooth.
Make sure the silicone tray is completely clean and dry. Set the tray onto a plate, tray, or cutting board so you have a solid base as some silicone molds are a little flimsy. This will make it easier to transfer to the freezer.
Pour or spoon the chocolate into each heart-shaped well and use a rubber spatula to evenly spread the chocolate into every corner of the mold.
Place the silicone tray in the freezer for about 5-10 minutes.
Remove from the freezer and add a second layer of chocolate anywhere that seems a bit thin, such as the top edges of the hearts.
Return to the freezer for about 5 more minutes.
While those are cooling get the marshmallows and latte mix ready.
Remove the tray from the freezer and carefully take one heart out of the mold at a time. You’ll want to work a bit carefully to help keep fingerprints off the chocolate, I will sometimes wear gloves to help with this.
Set the hearts on the cold tray while you heat a plate in the microwave. Then use this heat to gently melt the edges of the hearts so you’ll have a smoother seam between the two halves. Repeat with all of the hearts.
Spoon the latte mix and marshmallows into half of the hearts.
Heat the plate again if needed and then heat the edges of the empty hearts again, one at a time, and set onto one of the filled hearts. They will bond together quickly so you’ll want to focus on finishing one before moving to the next.
Once all of the hearts are filled and sealed together you can melt the chocolate to drizzle on top.
I used the same exact chocolate that was used for the hearts. You can use different chocolate, just make sure it has some coco butter listed in the ingredients to help with drizzling vs clumping.
Cut only a tiny hole at the end of the piping bag--after the chocolate is transferred into it and melted-- then quickly move your entire arm back and forth as you drizzle the hearts one at a time. Immediately add the sprinkles on top. Then repeat with the remaining hearts.
You may return the hearts to the freezer (or fridge) for a few minutes to have the drizzle chocolate set up or let them sit at room temperature.