For meringue, in a large bowl, beat the egg whites, vanilla, salt and vinegar on medium speed until soft peaks form. Gradually beat in sugar, 1 tablespoon at a time, on high until stiff peaks form.
Gradually beat in sugar, 1 tablespoon at a time, on high until stiff peaks form. Fold in chocolate chips.
Drop meringue into eight mounds on parchment-lined baking sheets. Shape into 3-in. cups with the back of a spoon.
Bake at 275° for 45 minutes or until set and dry. Turn oven off; leave meringues in oven for 1-1/2 hours.
Meanwhile, in a large heavy saucepan, combine eggs and sugar. Stir in the lemon juice, butter and lemon zest. Cook and stir over medium-low heat for 15 minutes or until mixture is thickened and reaches 160°. Transfer to a small bowl; refrigerate until chilled.
For ganache, in a small saucepan, melt chocolate with cream over low heat; stir until blended. Remove from the heat; stir in vanilla. Cool slightly.
Just before serving, spoon lemon curd into meringue cups. Drizzle ganache around meringue.