In a medium saucepan, rub the lemon zest into the sugar to release the oils. Then add the eggs, egg yolks, and salt. Whisk until combined. Then, while continuously whisking, add in the lemon juice.

Place the pot over medium-low heat and continue whisking until the mixture thickens, about 5 minutes. Then remove the pot from the heat and whisk in the butter. Strain the lemon curd into a small bowl, cover the surface with plastic wrap, and refrigerate for at least 1 hour or until completely chilled.

In a large bowl, use a whisk or hand mixer on medium speed to combine the black sesame paste, softened butter, granulated sugar, and brown sugar until smooth. Next, beat in the egg and vanilla extract. Add the baking powder, baking soda and salt; mix again until just combined. Now fold in the flour until no specks remain. The dough should be soft and supple. Transfer to the fridge to chill for about 30 minutes.

Meanwhile, preheat the oven to 350F. Line two baking sheets with parchment and set aside. Using a 1-ounce cookie dough scooper (or 2 tablespoons), scoop out a ball of dough. Roll the dough into a ball using the palm of your hands. Transfer to the cookie sheet being sure to space the cookies about 2-inches apart since they’ll spread a bit. You can fit at least 9 cookies per sheet.

Transfer to the oven and bake for 10 minutes, until the cookies have spread and domed. As soon as you remove the baking sheet from the oven, quickly use a tablespoon to make an indentation at the center of each cookie. (As the cookies cool, it will be harder to make the indentation.)

Transfer the cookies to a cooling rack until they’re room temperature. Once cooled, add a teaspoon of the lemon curd to the center of the cookies and sprinkle with a few black sesame seeds. These cookies will keep in an airtight container for up to 2 days.