Preheat oven to 350 degrees F (175 degrees C) and position a rack in the upper third of the oven.

Line two baking sheets with parchment paper.

In a medium bowl, whisk together the flour, baking soda, and salt until well combined.

In the bowl of a stand mixer fitted with a paddle attachment, beat the butter at medium speed until just softened and broken up.

Add the 3/4 cup dulce de leche, brown sugar, and granulated sugar to the butter mixture.

Beat on medium speed until light and fluffy, about 3 minutes.

Add the eggs one at a time, beating to incorporate after each addition.

Reduce the mixer speed to low.

Add the dry ingredients all at once.

Mix only until the flour is just incorporated, be careful not to overmix.

Finish mixing with a spatula if needed to ensure all ingredients are combined.

Spoon the dough onto the lined baking sheets using a heaping teaspoon of dough for each cookie, leaving 2 inches of space between each.

Bake the cookies for 10 to 12 minutes, or until they are honey brown with a light crust and still soft when they come out of the oven.

Let the cookies rest on the baking sheet for a minute or two before removing to cool completely on a wire rack.

Once the cookies are completely cooled, spread them with dulce de leche.

Sprinkle with a bit of sea salt if desired.

Keep well wrapped for up to four days.