for the dulce de leche chips
1 quart whole milk
12 ounces sugar, approximately 1 1/2 cups
1 vanilla bean, split and seeds scraped
1/2 teaspoon baking soda
for the brownies
1/3 cup Dutch-processed cocoa
1/2 cup plus 2 tablespoons boiling water
2 ounces unsweetened chocolate, finely chopped
4 tablespoons (1/2 stick) unsalted butter, melted
1/2 cup plus 2 tablespoons vegetable oil
2 large eggs
2 large egg yolks
2 teaspoons vanilla extract
2 1/2 cups sugar
1 3/4 cups unbleached all-purpose flour
3/4 teaspoon table salt
1/2 teaspoon cayenne pepper
1 teaspoon ground cinnamon
1 1/2 cups dulce de leche chips
First make the dulce de leche chips. You can make these up to a week in advance and keep in the freezer.
Combine the milk, sugar, vanilla bean and seeds in a large, 4-quart saucepan and place over medium heat. Bring to a simmer, stirring occasionally, until the sugar has dissolved. Once the sugar has dissolved, add the baking soda and stir to combine. Reduce the heat to low and cook uncovered at a bare simmer. Stir occasionally, but do not re-incorporate the foam that appears on the top of the mixture. Continue to cook for 1 hour. Remove the vanilla bean after 1 hour and continue to cook until the mixture is a dark caramel color and has reduced to about 1 cup, approximately 1 1/2 to 2 hours. Strain the mixture through a fine mesh strainer. Cool to room temperature.
Line a baking sheet with wax paper. Fill a piping bag with the dulce de leche and pipe 1/4 teaspoon drops onto the wax paper, approximately 1 an inch apart. Place baking sheet into the freezer and let the chips harden completely like little chocolate chips. Keep in the freezer until ready to use.
To make the brownies, heat oven to 350F. Make a foil sling for your 13 x 9 inch pan. Spray with nonstick cooking spray.
Whisk cocoa and boiling water together in large bowl until smooth. Add unsweetened chocolate and whisk until chocolate is melted. Whisk in melted butter and oil. Add eggs, yolks, and vanilla and continue to whisk until smooth and homogeneous. Whisk in sugar until fully incorporated. Add flour, salt, cayenne and cinnamon and mix with rubber spatula until combined. Fold in dulce de leche chips.
Scrape batter into prepared pan and bake until toothpick inserted halfway between edge and center comes out with just a few moist crumbs attached, 30 to 35 minutes.
Transfer pan to wire rack and cool 30 minutes. Using foil overhang, lift brownies from pan. Return brownies to wire rack and let cool completely, about 1 hour more. Cut into 2-inch squares and serve.