Grab a cookie sheet and line with parchment paper
In a large-sized bowl, cream the butter and sugar using a hand mixer on medium
Then mix in the egg and egg yolk till combine
Next, add the vanilla extract and continue to cream with hand mixer on medium until mixture becomes light and fluffy
Now, add the flour and salt in the bowl
Using the hand mixer, start slow then move to medium until the flour is fully combine
Roll the cookie dough into 1 inch balls and place on the cookie sheet that was lined with parchment paper
With your index finger or the back of tbsp measuring spoon, make a small indent in each cookie dough ball
Make space in the fridge and place the cookie sheet in to chill for 30 minutes
Preheat oven to 350 degrees at the last 10 minutes
When times up, place cookies in the oven to bake for 10 minutes
Clean the hand mixer whisks while the cookies bake, you will need to use them again for the glaze
Remove the cookies from the oven and if any of the indents filled in, carefully make new indents for the lemon curd
Now, place a 1/2 tsp to 1 tsp of lemon curd in the indents of each cookie
Return the cookie sheet back to the oven and bake for another 6 to 8 minutes or until the bottom of the cookie is a light golden brown
Pull cookies out of the oven and allow the cookies to cool completely
Sprinkle lemon zest on top (if preferred).
Enjoy!