Preheat oven to 225°F. Line a baking sheet with parchment paper sprayed lightly with nonstick spray.
In the bowl of a stand mixer fitted with the whisk attachment, beat egg whites on medium-high speed for 1 minute until frothy.
With mixer still going, add in sugar very slowly, followed by the cream of tartar and vanilla until combined. Turn mixer off and scrape sides of the bowl to combine. Continue beating for 2-3 minutes on high speed until meringue is glossy, stiff peaks form, and mixture is smooth and not grainy. If sugar isn’t completely dissolved continue mixing in 30 second increments until it’s smooth between your fingers.
Fit a piping bag with a large star tip and fill piping bag with meringue. Pipe your meringue into 2-3 inch hearts.
Bake the piped meringues for 60 minutes. Turn the oven off, without opening the door. Allow the meringues to sit in the warm oven for another 1 hour.
Remove meringues from oven. Carefully remove meringues from baking sheet and transfer to a wire rack to cool completely.
Once cool melt your chocolate with the coconut oil according to the package directions. The coconut oil gives it a smoother consistency. Dip half of your heart meringue into the melted chocolate letting the excess drip off. While the chocolate is wet, sprinkle with some sprinkles. As soon as the chocolate is set, serve or store in an airtight container.