Ingredients
Shortbread crust
- 1 cup unsalted butter, room temperature
- 1/2 cup granulated sugar
- 1 1/2 teaspoons vanilla extract
- 2 cups all-purpose flour
- 1 tablespoon cornstarch
- 1/2 teaspoon salt
Shortbread crusts like this use a high butter-to-flour ratio plus cornstarch for a tender, slightly sandy texture that holds up under heavy toppings.
Brownie and caramel layers
- 1 box brownie mix, plus ingredients listed on the box
- (Example: 1/2 cup vegetable oil, 3 tablespoons water, 2 eggs)
- 2 cans dulce de leche (sweetened, caramelized milk)
Starting with a boxed mix is common in multi-layer brownie bar recipes; it guarantees a consistent, fudgy texture while you focus your effort on the other layers.
Ganache and toppings
- 8 ounces good-quality semi-sweet chocolate bars, finely chopped
- 1 cup heavy whipping cream
- 2/3 cup pecans, roughly chopped (optional but highly recommended)
- Coarse or flaky salt (optional)
Ganache made with chopped chocolate and hot cream sets into a soft, sliceable top layer that looks bakery-level and enhances the “millionaire” feel.
Step-by-step instructions
1. Make the shortbread crust
- Preheat your oven to 350°F (177°C). Line a 9×13-inch baking dish with parchment paper, leaving a 2-inch overhang on the long sides to help lift the bars out later. Lightly grease the parchment.
- In the bowl of a stand mixer fitted with the paddle attachment, or in a large bowl with a hand mixer, beat the room-temperature butter, granulated sugar, and vanilla extract until smooth and creamy. Scrape down the sides of the bowl.
- Add the flour, cornstarch, and salt. Mix on low just until everything is incorporated and a soft, slightly sticky dough forms; avoid overmixing so the crust stays tender.
- Press or spread the dough evenly into the bottom of the prepared baking dish using an offset spatula or your fingers.
- Bake for 21–24 minutes, or until the crust feels firm and the edges look very lightly golden.
Let the crust cool for 10–15 minutes. Giving each layer time to cool is crucial; rushing can cause layers to blend and lose definition.
2. Bake the brownie layer
- Reduce the oven temperature to 325°F (163°C).
- Prepare the brownie batter according to the package directions (for example, whisk together brownie mix, oil, water, and eggs until combined).
- Pour the brownie batter over the cooled shortbread crust and spread it into an even layer.
- Bake for 28–30 minutes. Check doneness by inserting a toothpick into the center: it should come out with a few moist crumbs but no wet batter. The brownies will firm up as they cool.
- Let the brownie layer cool completely before adding the dulce de leche.
Cool-down time keeps the caramel from melting into the brownies instead of sitting in its own lush layer.
3. Add the dulce de leche
- Open 2 cans of dulce de leche and scoop the contents over the cooled brownie layer.
- Using an offset spatula, spread the dulce de leche into an even layer from edge to edge.
If the dulce de leche is too thick to spread easily, warm it gently in the microwave in short bursts and stir until it’s smooth and spreadable; this is a common trick in caramel-layer bar recipes.