Preheat the oven to 375°F and line two sheet pans with parchment paper.
Cream the butter with a hand mixer until fluffy and light.
Add the powdered sugar and flour to the butter and slowly incorporate.
Add in egg and vanilla and mix until combined.
Roll generous tablespoonfuls of dough into a ball and coat with granulated sugar.
Place the cookie balls on the parchment-lined sheets, spacing them apart by 2 inches. Using a round ½ teaspoon measuring spoon, create a thumbprint on each cookie, careful not to go too close to the bottom of the cookie.
Add a spoonful of lemon curd to each cookie, trying not to overfill.
Bake, until the edges of the cookie are just beginning to brown, about 15 minutes. Remove from pan after baking and cool on a wire rack.
Nutrition facts are sometimes provided below and are calculated using an online calculator. With specific brands of ingredients and additions, omissions, or substitutions the nutrition facts may change. We encourage you to use your own nutrition facts caculator to obtain the most accurate nutrition facts for your meal.