Preheat the oven to 350 degrees F.
Place the walnuts on a baking sheet and toast them in the oven for about 10 minutes. Let the nuts cool (leave the oven on). When the walnuts are cool enough to handle, put them in a food processor and pulse 2 or 3 times, until all of the large pieces have been chopped.
In a medium bowl, whisk together the flour and salt. Add the chopped walnuts, and stir to combine.
In the bowl of an electric mixer fitted with the paddle attachment, beat together the butter, cream cheese, and sugar on medium speed until the mixture is light yellow and fluffy, about 3 minutes. Scrape down the sides of the bowl with a rubber spatula. Add the vanilla and mix on medium speed for 1 minute. Reduce the mixer speed to low, add the flour mixture, and mix for 20 seconds. Take the mixing bowl off the mixer and finish mixing the dough with a rubber spatula.
Scoop out a small round of dough, about 1 1/2 tablespoons in size. Roll the scoop into a ball, place it on a parchment paper-lined baking sheet, and gently press the ball. Repeat, leaving 1 inch between cookies.
Bake the cookies for 14 to 16 minutes, until they are light brown around the edges. Transfer the cookies to a wire rack and let them cool.
If you can find dulce de leche at your market and you're in a sassy mood, go ahead and sandwich two of these cookies together with some of the caramel spread.
Reprinted with permission from One Girl Cookies by Dawn Casale and David Crofton, Clarkson Potter copyright (c) 2012