Preheat the oven to 350°F. Butter a 9x13-inch pan.
In a large bowl, whisk the 3 cups of flour with the baking soda and salt. Add the butter, oats and brown sugar and use an electric mixer to combine. In a small bowl, mix the dulce de leche with another 3 tablespoons of flour.
Pat half of the oat mixture into the baking pan. Bake for 15 minutes. Scatter half of the chocolate chips and pecans over the crust. Dollop half of the dulce de leche mixture on top. Crumble the remaining oat mixture evenly into the pan. Cover with the remaining chocolate chips, pecans and dollops of dulce de leche.
Bake for about 35 minutes, or until the edges are set. Let stand, uncovered at room temperature overnight. Cut the carmelitas into bars and serve.
Notes
Purchase pre-made dulce de leche in a can or bottle. Nestle makes it (among other manufacturers.) We find ours in the Latin section of our market.
Once cooled, the carmelitas can be kept in an airtight container at room temperature for up to 3 days or frozen for up to 1 month.