In a medium sized bowl, combine cold butter, flour, cornstarch, sugar, salt, and lime zest.
Using a pastry cutter or two knives, mix all of the ingredients together until mixture resembles coarse meal.
This will take a couple of minutes so be patient while it all comes together. For best results, make sure that the butter is cold, but not frozen.
Once your crust is complete, take a 9x13 parchment lined pan and place crust into the pan. Press down with the palm of your hand and bring the crust to the edges of all sides of the pan.
Poke the crust all over with a fork and place crust in the oven to bake. Bake at 350 degrees for 15 - 20 minutes until edges are golden brown and the middle is firm to touch.
While crust is baking prepare lime topping. In a medium sized bowl, whisk together sugar, flour, eggs, lime juice, and zest. Add a drop or two of green food coloring, if desired. Make sure the eggs are completely incorporated into the mixture. Set aside until crust is done baking.
Once crust has baked, pour lime mixture over the top and place pan back into the oven and bake for an additional 20-25 minutes. Bars should be set and no longer jiggly.
Remove from oven and allow lime bars to cool completely before sprinkling with powdered sugar and cutting.
Calories are automatically generated. For best results calculate based on your exact ingredients.
Some recipes call for the crust to cool completely before it goes back into the oven. I haven’t seen a difference with either method and I haven’t had problems pouring the lime curd over the top of the crust while it’s still hot and placing it back into the oven.
For a thicker crust/lime topping ratio, you can use an 8x11” pan and increase the cook time on the crust and topping 5 - 10 minutes.
It’s very important to thoroughly mix the eggs into the lime topping or the bars will end up like scrambled eggs.
Store in the refrigerator for up to 4 days. You may freeze these for up to 3 months. I don’t recommend using powdered sugar on frozen bars until they are taken out of the freezer and thawed. Thaw overnight in the refrigerator after freezing.
The lime topping has a smooth and silky texture that pairs well with the crunchy crust. The zest in the crust ties all of the flavors together!