Heat the oven to 350º. Place the pecans on a single layer on a baking sheet and bake until toasted, about 7 minutes. Coarsely chop and set aside. Line an 8 x 8-inch baking pan with foil, leaving several inches overhang on the sides. Grease the foil with butter or cooking spray and set aside.

Place the butter and bittersweet chocolate in a medium bowl set over a pot of simmering water, making sure the water does not touch the bowl. Stir occasionally until melted and smooth, then remove from heat. Whisk in the sugar, eggs and vanilla and continue whisking until glossy and thick, about 2 minutes. Stir in the flour and salt and mix until just blended. Transfer the batter to the prepared pan and spread evenly.

Stir half of the chopped pecans into your prepared caramel sauce (if you use store-bought, you may have to heat it up slightly before doing this). Drop the caramel pecan mixture by spoonfuls onto the brownie batter. Gently swirl with a wooden skewer or thin metal spatula. Scatter the remaining pecans and chocolate chips on top.

Bake for about 35 minutes. Set the pan on a wire rack and allow brownies to cool completely in the pan. Grab the foil overhang to lift the brownies out of the pan. Cut into squares and serve. Extra brownies (if there are any!) can be kept in an airtight container up to a week and will stay even fresher if wrapped individually in plastic wrap.