Description
French Custard Cake is a delightful and elegant dessert featuring a creamy vanilla custard filling nestled in a buttery Biscoff cookie crust, topped with fresh blueberries and a luscious mascarpone lemon buttercream. Complemented by a vibrant homemade blueberry sauce, this cake blends rich textures and bright, fresh flavors perfect for special occasions or a refined treat.
Ingredients
Scale
Custard Cake Filling
- 2 cups heavy cream
- 3 1/2 tablespoons butter
- 1 teaspoon vanilla extract
- 3/4 cup all-purpose white flour
- 1 1/4 cups superfine caster sugar (or white granulated sugar)
- 2 eggs (at room temperature)
- 2 egg yolks (at room temperature)
- 1/2 teaspoon salt
- Zest of one lemon
- 1 3/4 cups blueberries
- Extra butter for the mold
Biscoff Crust
- 3 cups Biscoff cookie crumbs
- 10 tablespoons unsalted butter (melted)
- 2/3 cup granulated sugar
Blueberry Sauce
- 6 cups fresh blueberries (frozen work too)
- 1 1/2 cups water
- 1 1/2 cups sugar
- 6 tablespoons cornstarch (mixed with 6 tablespoons cold water)
- 2 tablespoons vanilla extract
Mascarpone Lemon Buttercream
- 1 stick butter (softened to room temperature)
- 5 oz mascarpone cheese (at room temperature)
- 2 1/2 cups powdered sugar
- Zest of one lemon
- Pinch of salt
- Heavy cream (optional, to adjust consistency)
Instructions
- Custard Cake Filling Preparation: In a large bowl, whisk together eggs, egg yolks, flour, sugar, lemon zest, and salt until well combined. Set aside.
- Heat Heavy Cream: In a small saucepan, heat the heavy cream over medium heat until it begins to boil, then remove from heat and stir in vanilla extract.
- Temper Eggs: Slowly pour one-third of the hot cream into the egg mixture, whisking constantly to prevent cooking. Then whisk in half of the remaining cream slowly, followed by the rest of the cream, ensuring the mixture is smooth.
- Cool Custard: Cover the custard mixture with plastic wrap and let it cool at room temperature for 20 minutes before refrigerating for one hour.
- Biscoff Crust Preparation: Preheat the oven to 350°F (177°C). In a food processor, pulse Biscoff cookies until finely ground, yielding 3 cups of crumbs. In a medium bowl, mix crumbs with melted butter and granulated sugar until fully combined.
- Form and Bake Crust: Press the crumb mixture firmly into the bottom and slightly up the sides of a 10-inch springform pan to create an even crust. Pre-bake for 7 minutes. Optionally chill for 2 hours for a no-bake variant.
- Assemble the Cake: Butter the edges of the springform pan. Layer 1 3/4 cups fresh blueberries evenly over the baked crust. Pour the chilled custard filling over the berries.
- Bake Custard Cake: Bake the assembled cake at 350°F (177°C) for about 50 minutes, or until the top is golden brown and the custard is set. Remove from oven and cool completely on a wire rack.
- Prepare Blueberry Sauce: While cake bakes or in advance, combine blueberries, water, and sugar in a large saucepan over medium heat. Stir gently to avoid crushing berries and bring to a low boil.
- Thicken Sauce: Mix cornstarch with cold water to create a slurry. Slowly whisk slurry into the simmering blueberry mixture. Cook until sauce thickens and coats the back of a spoon, about 10 minutes. Remove from heat and stir in vanilla extract. Cool completely before using.
- Make Mascarpone Lemon Buttercream: Using a stand mixer with a wire whisk attachment, beat softened butter and mascarpone on medium speed until smooth and creamy, about 2–3 minutes. Gradually add powdered sugar ½ cup at a time, mixing well. Add lemon zest and a pinch of salt. If needed, add heavy cream, one tablespoon at a time, to reach the desired frosting consistency.
- Finish and Serve: Once the cake has cooled, spread the mascarpone lemon buttercream evenly over the top. Drizzle the cooled blueberry sauce generously over the frosting. Slice and serve.
Notes
- The custard filling requires tempering with hot cream to avoid curdling the eggs.
- Ensure the Biscoff crust is tightly packed to prevent custard leakage.
- You can prepare the blueberry sauce several days ahead and refrigerate.
- For a firmer frosting consistency, refrigerate the mascarpone buttercream briefly before frosting the cake.
- Half the blueberry sauce recipe if using less sauce or to avoid leftovers.
- The crust can be chilled for 2 hours instead of pre-baking for a no-bake dessert variation.
- Use room temperature eggs and dairy for smooth custard texture.
- Prep Time: 30 minutes
- Cook Time: 1 hour 10 minutes
- Category: Dessert
- Method: Baking
- Cuisine: French
Keywords: French custard cake, Biscoff crust, blueberry sauce, mascarpone buttercream, custard dessert, elegant dessert
