Caramel-Marshmallow Brownies

Sweet and gooey cookie bars are incredibly easy to make and great to serve. These brownies are sure to be a hit at any event, from a birthday party to a baby shower, or as an after-dinner treat for your family.
Preheat the oven to 350 degrees. Line an 8-inch square metal baking dish with a 12-inch sheet of foil, then brush the foil.Melt the butter and chocolate in a medium saucepan over medium-low heat, whisking lightly until smooth and shiny. Remove from heat.Whisk together the sugar and salt, then beat the eggs one at a time until smooth. Add the vanilla extract, then the flour. Place on the prepared baking dish and evenly sprinkle the walnuts on top.Bake the brownies until they are set and slightly springy to the touch, about 20 minutes. Remove the pan from the oven and turn off the heat. Sprinkle chocolate chips and marshmallows on top, return the pan to the oven for 2 minutes, then transfer the pan to a wire rack to cool.Combine the caramel and cream in a small bowl and microwave on medium (50%) power for 1 1/2 minutes; stir with a fork until smooth. Drizzle the caramel cream over the brownies, then let them cool completely.When the brownies are cool, remove the foil from the baking tray, then transfer them to a board. Cut the brownies into four pieces, then cut each quarter into four separate pieces.