• Preheat the oven to 350F and line a 9x13 inch glass or ceramic baking pan with parchment paper

Crust:

• To make the crust, add the powdered sugar into the bowl of a stand mixer fitted with the paddle attachment. Stir in the flour. Add the butter and vanilla bean paste and beat on low speed until a smooth dough forms.
• Press the dough evenly into the pan using a piece of plastic wrap to help smooth the dough evenly. Line the crust with parchment paper and fill with baking weights.
  
• Bake the crust until it is a deep golden brown, about 40 minutes. Bake for the first 30 minutes with the pie weights. After 30 minutes, remove from the oven and remove the pie weights and parchment. Place the crust back into the oven for an additional 10-15 minutes until lightly golden

Yuzu Curd:

• In a saucepan that a bowl can sit on top of or double broiler, pour about 2 inches of water and bring it to a simmer. (The bowl should be able to sit on top without touching the water)
• In a bowl, add yuzu juice, eggs, egg yolks, sugar, and salt. Place the bowl on the saucepan and whisk the curd continually until the mixture becomes very think, this will take about 10-12 minutes (or it is 180° F on a thermometer.)
• Remove the bowl from the saucepan and cool until it reaches 140° F, stirring from time to time to release the heat.
  
• While it is cooling, cut butter into 1-tablespoon cubes. When the curd is ready, whisk in the butter 1 tablespoon at a time, stirring until melted after each piece.
• Once all the butter is added, the curd will be pale yellow and thick.
  
• Pour over your baked shortbread and press a piece of plastic wrap on top to prevent the curd from forming a skin. Set in the fridge for 3-4 hours or overnight until set before topping with meringue.

Meringue:

• Use a double boiler or create one using a bowl and pan. Fill the pan with 2” warm water and place a bowl over the pan so it can heat the egg whites with the steam, but it should not touch the bottom
• Add egg whites, sugar, and cream of tartar to the bowl. Place the bowl over the warm water. The pan should not touch the bottom but be heated by the steam
• On low, heat the egg white mixture stirring constantly until gently warmed and the sugar is dissolved. Be very careful at this stage to not let the egg whites cook. Scrape the sides of the pan, stir constantly, and remove when sugar dissolves
• Once dissolved, whip the egg whites on high until stiff peaks form. The mixture will be very glossy and thick. When you place the whisk into the eggs and pull up, it should create a peak. Once it reaches this point, add in the vanilla and mix to evenly combine.
• Add the meringue over the set, chilled bars. Toast with a blow torch or in an oven on the broil setting for ~1-3 minutes keeping a close eye so it does not burn.
  
• Slice and serve. The bars should be kept in the fridge after topping.