Lemon Meringue Squares

Preheat the oven to 350 degrees. Butter a 9 x 13-inch metal baking pan.

Make the crust. In the bowl of an electric mixer fitted with the paddle attachment (or by hand), mix (don't whip) 1 ¹⁄₂ sticks of the room temperature butter and ¹⁄₂ cup of sugar until combined. Stir in ¹⁄₂ tsp of vanilla extract and 1 tbl of warm water. In a separate bowl, combine 1 ¹⁄₂ cups of flour and ¹⁄₄ tsp of salt. With the mixer on low, slowly add the flour mixture and mix until it's in big crumbles. Transfer it to the prepared pan and pat it evenly in the bottom of the pan, covering it completely. Bake for 20 to 22 minutes, until the crust is nicely browned. Set aside leaving the oven on.

Make the filling. PLace 1 ¹⁄₂ cups of sugar, 3 tbl of flour, 1 tbl cream of tartar, ¹⁄₂ tsp of salt in a large saucepan. Whisk in 4 whole eggs and 6 egg yolks, lemon zest and lemon juice. Cook over medium-low heat for 10 to 12 minutes, until thick, stirring constantly with a wooden spoon. Off the heat, stir in the ³⁄₄ stick of diced butter and set aside.

Make the meringue. In the bowl of an electric mixer fitted with a paddle attachment (or by hand), beat the 6 egg whites, 1 tsp cream of tartar and a pinch of salt on high until light and foamy. Reduce the speed to low, slowly add ³⁄₄ cup sugar, then increase the speed to high and beat for 2 to 3 minutes, until the whites are glossy and form stiff peaks.

Assemble. Spread the filling over the crust, then spread the meringue over the filling covering it completely. Swirl the meringue with the back of a spoon to make lots of peaks. Bake for 10 to 20 minutes, until the meringue is nicely browned. Cool on a baking rack for at least 2 hours, cut into 12 bars. Squares can be served at room temperature or keep them in the pan, wrap tightly and store in the refrigerator for up to a week and serve cold.