01 -
On medium-low heat, warm the milk in a mid-sized pot until it just begins to steam. Lower the heat to keep it warm.
02 -
Whisk egg yolks with sugar, cornstarch, vanilla, lemon zest, and salt in a large mixing bowl until smooth and creamy.
03 -
Slowly pour about 1/4 of the hot milk over the egg mixture while whisking briskly. Blend in the remaining milk afterward.
04 -
Return everything to the pot. Stir constantly with a whisk over medium-low heat for 8-12 minutes until it thickens to soft peaks.
05 -
Once thick, move the custard to a bowl. Add the butter cubes and stir until smooth. Cover it directly with wrap and chill completely in the fridge.
06 -
Mix sugar with lemon zest in a small bowl until the flavor blends. Leave it aside for now.
07 -
Preheat oven to 175°C (350°F) and line two trays with baking paper.
08 -
Blend flour, baking soda, baking powder, and salt in a large mixing bowl. Put the mixture aside for later.
09 -
Using a stand mixer or hand mixer, beat the butter with sugar for 2 minutes on high until fluffy and light.
10 -
On medium speed, mix in the egg, lemon zest, and vanilla until the batter looks pale and airy (about 1-2 minutes).
11 -
Turn the mixer to low and slowly mix in the dry blend until a dough forms.
12 -
Form dough into balls using a cookie scoop. Roll each in lemon sugar, flatten gently, and space them evenly on the lined trays.
13 -
Bake cookies for 9-10 minutes. Let them cool on the tray for 5 minutes after removing from the oven. Use a round cutter to neaten the edges, if desired.
14 -
Transfer cookies to a rack and let them cool down all the way before the next step.
15 -
Pipe the chilled custard onto the cookies using a piping bag with a small round tip.
16 -
Sprinkle a teaspoon of granulated sugar on top of the cream. Use a kitchen torch to melt the sugar until golden and fragrant like toasted marshmallow.
17 -
Let the caramel cool for about 10 minutes before serving. Add the cream and caramel topping just before eating to keep the cookies firm.