Preheat oven to 275 degrees F. Line a large baking sheet with ungreased parchment paper or aluminum foil (dull side up). Draw eight 3 1/2-inch circles on the paper; set aside.
In a large mixer bowl, beat egg whites on low speed until foamy. Then, add one at a time, the cream of tartar and vanilla extract. Continue beating until the whites begin to hold their shape and become opaque. Increase the speed to medium-high and gradually add the sugar in a slow stream. Beat until the whites thicken and form stiff peaks (do not over beat).
Spread each circle with approximately 1/3 cup meringue; shape with back of spoon to make shells, building up sides to form shells.
Bake for 1 hour; turn off oven, leaving meringues in the over, with door closed, for an additional 1 1/2 hours. Remove baking sheets to wire racks. Let meringues stand 15 minutes; then carefully loosen them with a wide flat metal spatula or a sharp knife and transfer to wire racks. Let cool completely.
NOTE: Fully baked hard meringues may be stored for months in a tightly sealed container with waxed paper between any layers. If they should lose crispness, bake in a preheated 250 degree F. oven for 15 to 20 minutes.
To serve, fill with your favorite filling.
Meringue Dessert Shells Recipe: https://whatscookingamerica.net/eggs/meringueshells.htm