Scientifically Sweet: Creamy Coconut Lemon Squares

Sunday, April 21, 2013

Creamy Coconut Lemon Squares

Spring is here! At least it is on one side of the world.

Or is it? I don't know.

I'm sitting here in Australia where everything is opposite, so outside it is a breezy & sunny Autumn day averaging around 20 degrees C.

But, most of my family is sitting somewhere in Canada enjoying a supposedly Spring day averaging about 4 degrees C. 

That doesn't sound right, but let's just go with it. Since April is supposed to bring bright sunny skies and upper teens weather, I'm going to say that tangy and zippy Lemon Squares are in order!

These are ubiquitous. Everyone loves a good lemon bar - even the chocoholics who say it's not worth it if it ain't got chocolate in it will snatch up a lemon square off the dessert table.

Their beauty lies in their simplicity that comes through their flavour and preparation. This is an easy recipe and it always delivers. Of course, there are some tricks to this trade...

An over-heated oven and a last minute distraction, like when you suddenly realize The One With The Holiday Armadillo episode of Friends comes on TV, can knock the "creamy" right out of the delicious lemon custard in these Creamy Coconut Lemon Squares.

Like any baked custard, including Creme Brulee and Creme Caramel, gentle heating and caring attention are the key to creaminess. Ingredients like sugar and flour protect the egg proteins from coagulation to help guarantee silky smoothness. The final texture of lemon curd is mainly the result of egg protein coagulation which induces thickening, but this is only desirable when it occurs to the right degree and does not end up in the formation of grainy clumps of egg white. Heat and acid (from lemon juice in this case) promote coagulation or bonding among egg proteins, but sugar helps to control this by interacting with proteins and interfereing with their bonding.

Cream adds body and mouthfeel to make the lemon layer that much more luxurious. It also dilutes the custard which keeps the proteins physically farther apart so that they don't bond too quickly.

So you can see that beneath the image of a smiple recipe is still some major Science!

There's no science to coconut.
Coconut is here becuase it tastes amazing when paired up with lemon and deserves a starring role in this story.

Creamy Lemon Squares featuring Coconut!
Makes 16 bars 

For the crust:
1 cup plus 1 tbsp (150 g)  all-purpose flour 

¼ cup (40 g) icing sugar 
¼ cup unsweetened desiccated coconut
1/8 tsp salt 

1/2 cup (113 g) unsalted butter, slightly chilled and cut into small cubes 

For the filling:
2 large eggs 

1 egg yolk
¾ cup (150 g) sugar
1 tsp lemon zest 
1/3 cup fresh Meyer lemon juice
4 tsp all-purpose flour
pinch of salt
¼ cup 35% whipping cream 

Preheat oven to 350°F and line an 8-inch baking dish with parchment paper. 

In a medium bowl, sift together flour and icing sugar. Add coconut and salt and whisk to combine. Add butter and blend it into the flour mixture with your fingertips until mixture resembles coarse meal. Turn dough out into prepared pan and press it in an even layer using your hands. Bake for 23 minutes, until crust is lightly golden. 

Meanwhile, prepare filling. In a small bowl, rub sugar together with lemon zest until fragrant. Add flour and salt and whisk to blend evenly. Lightly beat eggs and yolk in another medium bowl and slowly whisk in sugar and lemon juice until well blended. Do not beat because we don’t want to incorporate air into the mix. Stir in cream until smooth. 

When base is ready, reduce oven temperature to 300°F and slowly pour filling over hot crust; return dish to oven and bake until filling is set, about 25 minutes. Do not over-bake or the filling will be rubbery instead of smooth and creamy. Cool completely in dish on wire rack, then cover and place in the refrigerator until chilled. 

Carefully lift parchment to remove bars from dish and place on a cutting board; cut into squares using a sharp knife and dust with powdered sugar just before serving. Store leftover bars in an airtight container in the refrigerator up to 3 days. 
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  1. Yummy!!! I love the combination of coconut and lemon! So fresh and summery! Your recipe sounds delicious and the pictures are so beautiful :)

  2. I love lemon bars and these look so perfect!

  3. I definitely love a good lemon bar - these look amazing, love the idea of adding coconut too!

  4. I had an idea but am not sure how it would turn out. What do you think about using 1 egg and 2 yolks for the filling. This leaves us with 2 whites to whip into a meringue like thing and add on top? Would that work? I know very little about baking/science behind it so please let me know.

    1. Hi Saad! Using more yolk in the filling will make it richer and softer. If you want to add a meringue layer (like lemon meringue pie), you should bake the recipe as is first (i.e. bake the filling over the crust until JUST barely set). Then put the meringue on top and cook until firm. You might want to add a little cornstarch in the filling to protect it from curdling.

  5. Hi, I've tried your recipe. They taste so good. Thank you so much for posting. By the way, may I ask you for some advice, as I want to improve on some areas. While preparing the filling, can I let the eggs, flour mixture go through sieve? I could still see some strains of yolk in the mixture and at the same time I didn't want to beat it. Also, when I store them in the fridge, there's a layer of water on the top of the filling? Is it because I didn't use air tight container? Lyn


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