In a large nonreactive saucepan, combine eggs, egg yolks, lemon zest, lemon juice, and sugar over low heat; whisk until incorporated. Add half the butter, and continue to whisk to prevent mixture from curdling. Once mixture thickens enough to coat the back of a spoon, add remaining butter and stir until very thick. (If mixture curdles, quickly remove from heat; strain into a bowl, and immediately cool over an ice bath.) Remove from heat, and continue stirring until lukewarm. (Speed up the cooling process by transferring the filling to a bowl resting in an ice bath.)

For Meringue

Mix eggs and sugar into a bowl and place over simmering water until the sugar is dissolved.  Transfer to stand mixer and mix on medium until soft peaks form. Add meringue into piping bag until tart has cooled.

Pipe the meringue onto the lemon tart and torch until brown.