Millionaire’s shortbread consists of a crisp shortbread base, chewy homemade caramel filling, and thick chocolate ganache top. It’s a decadently rich treat that lives up to every penny of its name! Recipe includes a how-to video!
Preheat oven to 350F (177C) and line a 13x9 baking pan with parchment paper.
Using an electric mixer, beat butter until well creamed.
1 cup unsalted butter, softened
Add sugars and beat until light and fluffy, about 30 seconds.
⅓ cup sugar, ⅓ cup light brown sugar, packed
Add egg yolk and vanilla extract and stir well, pausing to scrape down the sides and mixing until ingredients are well-combined.
1 large egg yolk, ¾ teaspoon vanilla extract
Add flour, gradually (about ½ cup at a time), pausing to scrape down sides of bowl. Halfway through the addition of the flour, sprinkle in the salt with the beater still running. Don't over-beat the dough, you want it to be slightly crumbly to make it easier to press into the pan.
½ teaspoon salt, 2 ¼ cups all-purpose flour
Drop dough over prepared pan and gently, firmly, evenly, press dough into the bottom of the pan. To make it easier, I usually lay a piece of wax paper over the dough and use the palm of my hand to smooth the surface (and then discard wax paper).
Bake on 350F (177C) for 20-25 minutes -- edges should be lightly golden brown.
Allow to cool while you prepare your caramel topping.
Caramel
Combine condensed milk, butter, brown sugar, corn syrup, and salt in a medium-sized saucepan over medium heat.
2 14-oz cans sweetened condensed milk, 14 Tablespoons unsalted butter, 1 cup light brown sugar, ⅓ cup light corn syrup, ¾ teaspoon salt
Stir frequently until butter is melted and ingredients are well-combined. Continue to stir constantly until mixture begins to boil (this could take several minutes, but you don't need to increase the heat).
Once mixture comes to a boil, reduce heat to a simmer (slowly bubbling), still stirring constantly. Continue to stir 10-15 minutes until mixture turns a rich caramel color and has thickened (should begin pulling away from the sides of the pot as you stir). If using a candy thermometer, the caramel should reach 225F (107C)
Remove from heat and immediately stir in the vanilla extract.
1 teaspoon vanilla extract
Pour evenly over prepared shortbread, use a knife to spread evenly if needed.
Allow to cool at room temperature for several hours or in the refrigerator for 1 hour before topping with chocolate.
Chocolate Topping
Combine chocolate chips and heavy cream in a small saucepan over low heat.
½ cup heavy cream, 2 cups semisweet chocolate chips
Stir frequently until chocolate is melted and mixture is smooth.
Remove from heat and allow chocolate to cool just slightly for about 5 minutes, and then evenly spread over prepared caramel layer. Wait several minutes/until chocolate begins to set and then sprinkle with sea salt.
sea salt for sprinkling
Allow chocolate to harden (I recommend placing in refrigerator for about 30 minutes -- my family prefers these treats refrigerated anyway) before cutting and serving.