Common Questions
Is dulce de leche the same as caramel?
Not exactly. Dulce de leche is typically made by slowly cooking sweetened milk until it turns thick and caramel-colored. Caramel is made by heating sugar. They taste similar, but dulce de leche has a milkier, rounder flavor.
Can I use lemon instead of lime?
Absolutely. Lime gives a punchy, almost tropical vibe. Lemon is a little softer and more classic. Use whichever you have.
Do I have to use fresh citrus juice?
Fresh is strongly recommended here because the citrus is the whole bright idea. Bottled juice can taste flat or slightly bitter in baked desserts.
My citrus layer looks a little lumpy. Did I mess up?
Probably not. Lumps usually mean the eggs started to set before they were fully mixed. Next time, whisk sugar and eggs until very smooth, then add citrus, then flour. You can also strain the mixture through a fine-mesh sieve before pouring.
How do I know the bars are done?
The center should look set and mostly matte, not wet or sloshy when you gently nudge the pan. The edges may look slightly puffed. A small jiggle in the very center is fine. If you like numbers, aim for about 170°F to 175°F in the center. The bars finish setting as they cool and chill.
Can I make this gluten-free?
You can try a 1:1 gluten-free flour blend in both the shortbread and the citrus layer. The shortbread may be a touch more delicate, so chill the bars well before slicing.
Can I bake this in a glass pan?
You can, but glass usually bakes a little differently. Start checking a few minutes later, and keep an eye on the edges so they do not overbrown.