Preheat the oven to 300°F. Line a 13”x18” rimmed baking sheet with parchment paper.
Add egg whites to a large bowl and beat until soft peaks form.
As you continue beating, add the sugar. Beat until stiff peaks form.
Add the cornstarch, lemon juice, and vanilla and beat for a few seconds or until combined.
Spread the meringue mixture on the baking sheet, evenly spread it, and then top it with the sliced almonds.
Bake for 30 minutes until the top of the meringue is golden.
Allow the meringue to cool slightly. Turn the meringue over and wrap it in a kitchen towel, allowing it to cool completely.