Tart:

1. Cut the butter into cubes.
2. Add the flour, powdered sugar, cut-up butter, and salt in the bowl of a food processor and pulse until it turn into small crumbs. Add the egg yolks and combine until it is well combined and forms into a dough. Take the dough out and wrap it with plastic wrap. Chill the mix in the fridge for 1 hour. 
3. Preheat the oven to 350 degrees Fahrenheit. 
4. Once the dough is chilled, roll it out so that it is larger than the tart pan. Place it over the pan and begin pressing it down and to the sides. Cut all the excess dough. Using a kitchen fork, pierce the crust and place in the freezer for 30 minutes. 
5. Take the dough out of the freezer and place parchment paper on top of it. Also, place uncooked beans on top of the parchment paper. This will ensure the tart crust doesn’t rise while baking. Bake for 20 minutes. 

Filling:

1. In a saucepan on medium heat, add the sugar, egg yolks, lemon zest, and juice. Make sure to stir all the ingredients constantly until they are warm. Add the butter and continue to mix it until it becomes thick (this takes about 8 minutes). Remove from heat. 
2. Add the white chocolate and stir the mixture until well combined and the chocolate has melted. 
3. Pour the mixture through a sieve to get rid of any lumps. Pour the mixture onto the tart crust and place in the fridge for at least 4 hours. 

Meringue:

1. Heat up a small pot with water, to create a double boiler. 
2. Add the eggs yolks and sugar in a mixer bowl and place about the boiling pot of water. Make sure to whisk every 20 seconds, until the sugar has melted. 
3. Place the mixer bowl back in the stand mixer and whisk at medium to high speed for one minute. Add the cornstarch and whisk on high for 9 minutes until stiff peaks. You will know the meringue is ready when you lift the bowl upside down and nothing moves.
4. Pipe or spoon the meringue on top of the lemon filling. Use a kitchen torch to brown the meringue. Hold the torch about an inch away so as to not over-burn the meringue.  
5. Serve and enjoy!