Lemon Curd Cookies

Ingredients for the cookie dough

• All-purpose.
• Cornstarch: it helps with the softness and melt-in-your-mouth feel of the cookies.
• Vanilla: I use pure vanilla extract or pure vanilla paste when available, but a good vanilla essence (artificially flavored) also works and is infinitely cheaper. 
• Powdered sugar: also called confectioners or icing sugar, you can easily buy it online. Domino powdered sugar is a very popular one.
• Salt: I like to use kosher salt when baking. But regular table salt works just fine.
• Baking powder: make sure it isn't expired.
• Unsalted butter.
• Egg: fresh, large.

See the recipe card at the end of this post for quantities.

How to make lemon curd cookies

• Mixing the dough: use an electric mixer if it's convenient, but it's easily mixed by hand if the butter is at room temperature and soft (but not starting to melt). If making a large batch, a stand mixer might come in handy.
• Measuring the cookies: use a cookie scoop so your cookies bake evenly. Leave roughly a 2-inch separation between each, so they can spread comfortably during baking. I use the small cookie scoop of this set that it’s 1.57 inches / 4cm in diameter for regular-sized cookies. 
• When to add the filling: after several tries, I settled on baking the cookies on their own for ⅔ of the total time, filling them with lemon curd, and returning them to the oven to bake a little more. It's the way to avoid drying the curd and having underbaked cookies.

If using an electric mixer, do so at the lowest speed after you add the flour. If mixing by hand, a rubber spatula is the easiest way to integrate the ingredients.

You should have a smooth dough with no dry spots. You can use it immediately or chill it for a few days, always well covered to prevent dryness.

Place the cookie dough balls with space between them to expand during baking, and make an indentation in each one. The back of a small measuring spoon is the best way.

Chill the dough balls before baking them. Don't fill the thumbprints to the brim to avoid spills in the oven, and do so halfway through baking.

Vintage Kitchen tip: I recommend doing a test run with a few cookies to check the amount of curd to use and the time they take to bake so they are soft and don't overflow. Don't bite into them immediately, as the filling might be hot. 

Storage

Allow them to cool completely at room temperature.

• Airtight container: store in a single layer, separating each one with wax paper to prevent sticking. I like to use metal tins.
• Room temperature: they keep well for up to 3 days.
• Refrigerated: keep them in the fridge for up to 1 week well covered to prevent dryness.
• Frozen: wrap them tightly in plastic wrap and place them in an airtight container or freezer bag. They will keep for up to 2 months. Let them come to room temperature before serving.

Kitchen notes

• Organization: read the recipe first and ensure you have ingredients at the correct temperature, equipment, and enough workspace. This will make the process so much easier.
• Baking time: keep in mind that all ovens and pans are different, even if they look the same or very similar. The baking time in my recipes is as accurate as it can be, but it might take you more or less time. You can use a thermometer(like the OXO oven thermometer) to check that your oven is at the right temperature. I recommend you keep track of how your oven works and what tiny details you need to adjust. 
• Make ahead:
  The lemon curd keeps for a week in the fridge and up to a month in the freezer, always in airtight containers.
  The cookie dough can be kept in the refrigerator for 3 days before using. Always cover it well to prevent dryness (I cover the bowl tightly with plastic wrap or transfer it to an airtight container with a lid).
• Test bake: I always recommend doing a test run with a few cookies to check the amount of curd to use and the time they take to bake so they are soft and not spilled. 
• Flavor variation: use lemon jelly or passionfruit curd. Flavor the dough with a touch of ground cardamom in addition to the lemon zest, use lime zest for a lemon-lime cookie, or a mix of citrus (orange, lemon, and lime).

Troubleshooting common issues

1. Cookies spreading too much could be because your dough is too soft or warm or it needs more flour. Make sure to chill the dough for at least 30 minutes before baking and use a good thumbprint recipe like this one, and you won't have this issue.
2. Lemon curd leaking out happens when the cookies have too much curd or the curd is too thin. Don't fill the indentation to the brim to avoid leakage. Use my homemade lemon curd that has the perfect consistency for these cookies.
3. Lemon curd sinking in the cookies could be because the cookies are not baked enough before adding the curd. That's why we half-bake them and then add the curd filling.