Pour the cherries and their juices into a medium saucepan, reserving 1/4 cup of the juice in a small bowl or measuring cup. Stir in the sugar and bring to a boil over medium high heat.
Meanwhile, whisk the cornstarch into the reserved cherry juice. When the cherries come to a boil, whisk the juice/cornstarch mixture into the cherries. Continue to simmer, reducing heat to medium if the boiling becomes rapid, until the juice thickens a syrupy consistency. Remove cherries from heat and stir in the vanilla and almond extract. Cool completely then chill until ready to use.
Heat oven to 200°F. Line a two baking sheets with parchment paper or silicone baking mats.
Add chickpea liquid, vanilla extract and cream of tartar to the bowl of a stand mixer (or a large bowl).
Beat on high speed and slowly add the sugar while the mixer is running. Continue beating until the mixture forms stiff peaks (about 6-7 minutes). Gently fold in the chopped chocolate.
Pipe or spoon the meringue into small dollops about 1 inch apart onto your prepared baking sheets.
Add cream, sugar and vanilla to a medium bowl or the bowl of a stand mixer. Beat on medium high speed until it forms soft peaks.
Break 2-4 (depending on how big they are) meringues per serving (total of 12-24 meringues) into pieces and place into 6 dessert bowls. Top each with cherry sauce and a large dollop of whipped cream. Sprinkle each with dark chocolate shavings. Serve immediately.
If you can't find canned cherries or you don't have time to make the sauce from scratch, you can substitute canned cherry pie filling, but it may be more filling and less cherries.
Make ahead instructions: The cherry sauce can be made ahead of time and refrigerated for up to a week. The meringues can be made ahead of time and stored in an airtight container at room temperature for up to a week. Make the whipped cream at the same time you're going to assemble the Eton Mess