Alfajores Recipe

To Make the Manjar Blanco:

1. Preheat the oven to 400 degrees F. Grab a small baking dish, a piece of foil and another larger baking dish that the smaller baking dish fits in.
2. Pour the sweetened condensed milk into the smaller baking dish and cover it with foil. Place the smaller baking dish in the larger baking dish and fill half way with water. We're going to be creating a water bath for the sweetened condensed milk to cook in. Transfer to the oven to bake for 1 hour to 1 hour and 15 minutes. You may need to re-fill it at the 45 minute mark since the water can evaporate.
3. Remove it from the oven and allow it to stand for about 15 minutes. This will cool it down so it's easier to handle.
4. Remove the foil from the baking dish and remove it from the water bath. Discard the cinnamon stick and pour the dulce de leche/manjar blanco into a glass or stainless steel bowl. Whisk it until it's smooth. This happens pretty quickly.
5. You can do this the day before if you like. This stays good in the fridge in an airtight container for up to two weeks. To temper the dulce de leche, transfer the container (with it's lid on and all) to a bowl with warm water. This will allow the dulce de leche to become smooth since the cold temperature from the fridge stiffens it quite a bit.

To Make the Cookies:

1. To the medium bowl, whisk together the all-purpose flour, sifted corn starch, powdered sugar and salt. Set aside. 
2. To the bowl of a stand-up mixer (you can also use a medium bowl and an electric hand-mixer), add the butter and vanilla paste or extract. Beat until smooth. Next, add the egg yolk and mix just until incorporated. 
3. Add all of the flour mixture and slowly mix it together (being sure not to go too quickly or else the flour will fly out of the bowl), until combined, about 1 minute. 
4. Scoop the dough out of the bowl and form it into a ball. Place it in the center of a sheet of plastic wrap and press it into about a 2-inch round. Wrap it tightly in plastic wrap and transfer to the fridge to chill for about 1 hour. 
5. Preheat the oven to 350 degrees F. 
6. When it’s done resting, in the fridge, transfer the dough to the center of a sheet of parchment. Place a sheet of parchment on top and roll it out slowly. (If it’s too cold, let it come closer to room temperature, about 10 minutes.) Roll it out until it’s about 1/2 to 1/4-inch thick.
7. Using a 3-inch cookie cutter, stamp out cookies, having them as close to each other as possible. Transfer the cookies (I found it easiest to use an offset spatula to pick up the cookies) to a parchment-lined baking sheet, spacing them about 2-inches apart. Transfer to the fridge to chill for about 10 minutes. Repeat until you work your way through all of the dough. I rerolled the dough about 2 more times. 
8. Score the tops of the cookies with a tines of a fork. Transfer to the oven to bake for about 11 to 13 minutes, until the cookies are a bit firm to the touch but have zero color on the edges. These cookies are baked just until set. Allow to cool on the baking sheets until room temperature. 

To Assemble the Alfajores:

1. When the cookies have cooled, flip half of the cookies on their opposite side. Transfer the manjar blanco to a piping bag with a piping tip attached (this part is optional). Pipe a round of manjar blanco on all of the cookies facing their opposite sides. 
2. Alternatively, you could also spoon the manjar blanco onto each of the cookies and smooth it out (gently because the cookies are delicate) using a butter knife. 
3. Top each of the cookies with another cookies and lightly press it down. Roll the sides in the sifted powdered sugar. Store in an air-tight container or bag for up to 3 to 5 days.