Favourite Lemon Squares

Lemon squares are the dessert that wins every potluck. The two-layer construction (a buttery shortbread base with a tart lemon curd baked on top) gives every bite a contrast between rich-tender and bright-tangy that nothing else quite matches.

The pre-baked crust is the technique that separates good lemon squares from soggy lemon squares. Fifteen minutes in the oven at 325°F (160°C) sets the shortbread firm enough that the wet lemon filling can’t penetrate. Pour the filling over the warm crust (not waited until cool) so the layers fuse during the second bake.

A touch of baking powder in the filling is the unusual addition that distinguishes this recipe. A quarter teaspoon lightens the curd just slightly, giving it a more aerated texture that’s not as dense as classic English lemon curd.

Three minutes of beating the filling is the right window. The mixture should slightly thicken before pouring. This pre-thickening helps the eggs cook evenly through the second bake without forming streaks or scrambled bits.

Pro Tips

• Use real butter instead of margarine for noticeably better flavor in the crust. The shortbread is mostly fat, so the fat quality matters.
• Zest the lemons before juicing. Squeezed lemon halves are impossible to zest.
• Wait until the squares are fully cool before dusting with powdered sugar. Warm squares dissolve the sugar instantly.
• Cut with a sharp knife wiped clean between cuts for clean square edges.

Variations

• Swap lemons for limes for key lime squares (use 2 tablespoons of zest, about 4-5 key limes).
• Add a tablespoon of fresh chopped basil or thyme to the filling for an herb-citrus twist.
• Sprinkle the top with a layer of shredded coconut after dusting with powdered sugar for textural contrast.