Cookie Swap Recipe: Dulce de Leche Sandwich Cookies

I'd have to say the crowning achievement of my cookie swap selection had to be this last cookie I am bringing to you. It's two dulce de leche cookies with a slather of creamy dulce de leche in between. Dulce de leche is similar to caramel. Where caramel is a concentrated sugar-water solution, dulce de leche is a concentrated sugar-milk solution. The result is a creamier more flavorful caramel that is the perfect accompaniment to most anything - cookies, cakes, fruit, a spoon.... Moreover, it's a complete cinch to pull together. Buy yourself a can of sweetened condensed milk. Open it. Pour it into an oven-safe casserole dish. Cover it tightly with aluminum foil. Set your oven to 425F. Put the condensed milk casserole dish into a larger, deeper oven-proof pan and fill this outer pan 1/2 way up the side of the smaller casserole with boiling water. Please be careful doing this. I usually pull out the rack in my oven half-way and put everything together there and then just slide in the rack when it's ready to bake.
Bake this for 1 1/2 to 2 hours. Replenish the water as necessary, keeping the level half-way up the side of the smaller dish. You will see the condensed milk become a caramel color. This is dulce de leche! It's that simple. Take out the dulce de leche and whisk fairly vigorously so as not to have a lumpy sauce. Let it cool completely and it can be stored in the refrigerator for up to one week. Alternately, you can purchase dulce de leche at your grocery store.
The dulce de leche sandwich cookies are one of the many things you can make with your dulce de leche. The cookie is fabulous on its own, but sprinkle a little sea salt before sandwiching each cookie and this cookie goes from fabulous to out of this world!

Dulce de Leche Sandwich Cookies
(Recipe from Baking: From My Home to Yours, Dorie Greenspan)

Ingredients:
2 1/2 c all-purpose flour
1 t baking soda
1/4 t salt
2 sticks (8 ounces) unsalted butter, room temperature
3/4 c dulce de leche, plus more for filling
3/4 c packed light brown sugar
1/2 c sugar
2 large eggs

Directions:
Preheat oven to 350oF and position a rack in the upper third of the oven. Line two baking sheets with parchment paper and set aside. In a medium bowl, whisk together the flour, baking soda and salt.
In the bowl of a stand mixer fit with a paddle attachment, beat the butter at medium speed until just softened and broken up a bit. Add the 3/4 c dulce de leche, brown sugar and granulated sugar. Beat on medium speed until light and fluffy, about 3 minutes. Add the eggs one at a time, beating to incorporate.
Reduce the mixer speed to low and add the dry ingredients all at once. Mix only until the flour is just incorporated. You may need to finish off the mixing with a big spatula.
Spoon the dough onto the lined baking sheets using a heaping teaspoon of dough for each cookie. The dough will be soft and this might be a bit messy. Leave 2 inches of space between each cookie.
Bake the cookies for 10 to 12 minutes. The cookies will be honey brown with a light crust, but still very soft when they come out of the oven. Let them rest on the cookie sheet for a minute or two before removing to cool.
Once the cookies are cooled completely, spread them with dulce de leche. You may sprinkle with sea salt (optional). Sandwich the cookies. Keep well wrapped for up to four days.

*How to make Dulce de Leche:

Set your oven to 425oF. Empty the contents of a can of condensed milk into an oven-proof casserole dish and cover tightly with aluminum foil. Place this dish within a larger dish with raised sides and fill the larger dish with water at least 1/2-way up the sides of the dish with condensed milk, providing a water bath for the condensed milk. Put this into the oven and bake for 1 1/2 to 2 hours. Replenish the water as necessary. When you take out the dulce de leche (remember, it will be very hot so be careful, especially when pulling the foil off!), whisk it for a few minutes until it becomes smooth. This may be stored in the fridge for up to 1 week.