Prep Time: 30 minutes (plus 1 hour chilling)
Cook Time: 35 minutes
Setting Time: 4 hours (minimum) or overnight
Total Time: Approx. 5 hours 5 minutes (mostly inactive)
Difficulty Level: Medium (Requires careful temperature control for the custard)
Intensity: Moderate Effort – A patient, rewarding bake.
Ingredients
For the Shortbread Crust:
1 ½ cups (190g) all-purpose flour
½ cup (65g) powdered sugar
¼ teaspoon fine sea salt
¾ cup (170g) unsalted butter, cold and cubed
For the Vanilla Custard Layer:
2 ½ cups (600ml) whole milk
¾ cup (150g) granulated sugar
¼ cup (30g) cornstarch
3 tablespoons (25g) all-purpose flour
¼ teaspoon fine sea salt
4 large egg yolks
2 teaspoons pure vanilla bean paste (or 1 tbsp vanilla extract)
2 tablespoons (30g) unsalted butter, at room temperature
For Assembly & Finishing:
½ cup (120ml) heavy whipping cream, cold
1 tablespoon powdered sugar
¼ teaspoon vanilla extract
Additional powdered sugar for dusting
Equipment Needed
8×8 inch (20×20 cm) square baking pan
Parchment paper
Mixing bowls (large and medium)
Whisk
Saucepan
Fine-mesh sieve
Hand mixer or stand mixer (for whipping cream)
Rubber spatula
Step-by-Step Instructions
Part 1: The Buttery Shortbread Base
Prepare the Pan: Preheat your oven to 350°F (175°C). Line your 8×8 pan with parchment paper, leaving an overhang on two opposite sides. This “sling” will allow you to lift the entire dessert out for easy cutting later. Lightly grease any exposed sides of the pan.
Make the Dough: In a medium bowl, whisk together the flour, powdered sugar, and salt. Add the cold, cubed butter. Using a pastry cutter, your fingertips, or a food processor, work the butter into the flour mixture until it resembles coarse, damp sand and begins to clump together when squeezed.
Parbake: Press this mixture very firmly and evenly into the bottom of your prepared pan. Use the flat bottom of a measuring cup to compact it completely—this prevents a crumbly base. Prick the dough all over with a fork. Bake for 18-22 minutes, or until the edges are just beginning to turn a very pale golden. It will not be fully cooked.
Cool Slightly: Remove the pan from the oven and place it on a wire rack. Let the crust cool while you make the custard. Do not turn off the oven.
Part 2: The Velvety Vanilla Custard (The Heart of the Recipe)
Prepare Your Mise en Place: In a medium saucepan, whisk together ½ cup (120ml) of the milk with the granulated sugar, cornstarch, flour, and salt until perfectly smooth and no lumps remain. Whisk in the egg yolks until the mixture is thick and pale yellow.
Heat the Milk: In a separate pot or in the microwave, heat the remaining 2 cups (480ml) of milk until it is just steaming and small bubbles form around the edges (do not boil).
Temper and Cook: While whisking the egg yolk mixture constantly, slowly drizzle in the hot milk. This gradual process, called tempering, prevents the eggs from scrambling. Once combined, return the entire mixture to the saucepan over medium heat.
The Critical Cook: Cook, whisking constantly and vigorously, especially in the corners of the pan. The mixture will begin to thicken. After 3-5 minutes, it will start to bubble with large, slow plops. Continue cooking and whisking for a full 2 minutes once it bubbles. This step is non-negotiable—it cooks out the raw starch flavor and ensures a perfect set.
Finish the Custard: Remove the pan from the heat. Immediately whisk in the vanilla bean paste and the room-temperature butter until the butter is fully melted and incorporated. The custard should be incredibly smooth, glossy, and thick enough to hold the marks of the whisk.
Strain and Pour: For absolute silkiness, pass the custard through a fine-mesh sieve directly onto the warm shortbread crust. Use a rubber spatula to spread it into a perfectly smooth, even layer, working quickly as it begins to set.
Part 3: Baking and Setting
Final Bake: Carefully return the pan to the oven (still at 350°F/175°C). Bake for 10-12 minutes. The custard should look set and may develop a very faint golden skin in spots. This brief bake stabilizes the custard layer.
Initial Cool: Place the pan back on the wire rack and allow it to cool completely at room temperature for about 1 hour.
Part 4: The Cream Topping & Final Assembly
Whip the Cream: In a chilled bowl, combine the cold heavy cream, 1 tbsp powdered sugar, and ¼ tsp vanilla. Whip with a hand mixer or stand mixer until it reaches stiff peaks.
Top and Chill: Gently spread the whipped cream over the completely cooled custard layer. Be delicate to avoid mixing the two layers.
The Essential Chill: Loosely cover the pan with plastic wrap and refrigerate for at least 4 hours, but ideally overnight. This extended chilling is crucial for the custard to firm up completely, making clean cuts possible.
Serve: Using the parchment paper sling, lift the entire block out of the pan and onto a cutting board. With a sharp, thin-bladed knife dipped in hot water and wiped dry between each cut, slice into 16 perfect squares. Dust generously with powdered sugar just before serving.
Chef’s Notes & Tips for Success
Vanilla is Key: Vanilla bean paste gives superior flavor and those beautiful specks, but a high-quality extract works perfectly. Avoid imitation vanilla.
Patience with the Custard: Constant whisking during the cook phase prevents lumps and scorching. Don’t rush the 2-minute boil.
Clean Cuts: The hot knife trick is your best friend. For ultra-sharp edges, chill the squares for 15 minutes after cutting.
Make-Ahead Magic: These squares taste even better the next day and keep beautifully, covered in the fridge, for up to 3 days.
Variation: For a citrus twist, add the zest of one lemon or orange to the shortbread dough.
Nutritional Information
(Per serving, 1 square. Information is an estimate calculated using a nutrition database.)
Calories: ~315 kcal
Total Fat: 19g
Saturated Fat: 11g
Cholesterol: 115mg
Sodium: 85mg
Total Carbohydrates: 33g
Dietary Fiber: 0.5g
Sugars: 20g
Protein: 4g