Lemon Meringue Bars

Billowy marshmallow meringue adds a fluffy texture to these zesty lemon bars. The rich, buttery crust and tangy lemon curd filling are complemented with a lofty marshmallow meringue. Lemonheads will appreciate their delicious sweet-tart flavor and textures, and even if you aren't one, I bet you will still enjoy the contrast in flavor!

What is cream of tartar?

It's not creamy, to begin with. It's a dry, powdery, acidic by-product of grape wine fermentation. Its scientific name is potassium bitartrate (hence the commercial name), which comes from potassium hydrogen tartrate or tartaric acid. However, it's usually called cream of tartar in the spice aisle.

Adding a little bit of cream of tartar to egg whites while beating—usually ⅛ teaspoon per egg white—not only speeds up the formation of foam, but it also helps to keep the structure of those tiny air bubbles you're creating. This means mile-high meringue pies, melt-in-your-mouth meringue, and other delicious fluffy cakes.

How do you brown meringue?

One of the most recognizable features of meringue is the browned top but how do you achieve that? If you have a broiler function on your oven, this will work nicely to do the job. But there is another way - a handheld kitchen torch!

Like a small fire lighter, these devices are used for different jobs around the kitchen, are inexpensive to buy, and are easy to use. One of the perfect examples of what they do is to brown the mixture on the top of the meringue to create that brown touch looks we all want.

What you need to make lemon meringue bars

For the Crust

• All-purpose flour
• Confectioners' sugar
• Unsalted butter
• Salt

For the Filling

• Large eggs
• Large egg yolks
• Granulated sugar
• Grated lemon zest
• Fresh lemon juice
• Salt

For the Meringue Frosting

• Large egg whites
• Granulated sugar
• Cream of tartar

How to make the recipe

Preheat the oven to 350°F. Cover an 8-inch square baking pan with parchment or foil, allowing it to extend over both ends.

Make the crust

In a food processor, combine the flour, sugar, and salt and pulse to mix. Add the butter and pulse until fine crumbs form.

Spread the mixture in the baking pan and press down to create an even layer.

Cook in the oven until set and golden brown, normally about 25 minutes. Remove to a wire rack to allow to cool.

Make the filling

In a large saucepan, combine the eggs, yolks, sugar, zest and juice, and salt. Simmer for 3 minutes while stirring constantly.

Reduce heat to low and simmer, whisking frequently, until thickened, about 8 minutes. Remove from the heat.

Pour the curd over the crust and smooth out any wrinkles. Cover with aluminum foil and bake for 10 minutes.

Remove from the oven and let cool completely. Refrigerate for at least 1 hour or overnight, or up to three days.

Meringue frosting

When you are ready to serve, make the frosting. Carefully remove the parchment from the bottom of the bars and transfer it to a baking sheet using a large, wide spatula.

In a metal mixing bowl, beat the egg whites, sugar, vanilla, and salt with a handheld mixer.

Set it over a pan of simmering water but make sure the bottom doesn't touch the water. Whisk until the sugar is dissolved and the mixture is warm to the touch, usually 3-4 minutes.

Remove from the water and beat on high speed until the mixture is glossy and stiff, usually about 5 minutes, before spooning the frosting over the filling and spreading to cover.

Finish the bars

Use a kitchen torch or a broiler to brown the meringue then pop in the refrigerator until serving.

To portion, use a knife dipped in hot water to cut into squares. Usually, 12 portions will be a nice number from this recipe but it is up to you.

Storing the recipe

You can store the lemon meringue bars in the refrigerator for 3-4 days in an airtight container.

I would avoid freezing them as the meringue will likely melt away and not be very tasty afterward.

Making meringue tips

Keep any yolk out of the whites. The fat in the yolks can interfere whipping the whites to a light and fluffy consistency. To avoid this, separate each egg over a small bowl to be sure the white is free of egg yolk before combining with other whites. Also, the yolks are less likely to break if you separate the eggs while they’re cold.

Use a clean, dry mixing bowl and beaters. Be sure the bowl  you are using to whip the whites is clean and dry, as any soap residue or water can interfere with whipping.Beat until stiff. The peaks of the beaten egg whites should stand straight up when the beaters are lifted