Name: French Blueberry Custard Cake with Biscoff Crust and Lemon Mascarpone Buttercream Recipe
Prep time: 30 min
Cook time: 1 h 10 min
Total time: 3 h
Cuisine: French
Ingredients: 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; 3 cups Biscoff cookie crumbs; 10 tablespoons unsalted butter (melted); 2/3 cup granulated sugar; 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; 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)

Jump to Recipe

Introduction

French Custard Cake is a delicate dessert featuring a creamy custard nestled on a crisp Biscoff cookie crust. Paired with fresh blueberries and a tangy lemon mascarpone buttercream, this cake offers a perfect balance of textures and flavors that’s sure to impress your guests.

A square slice of cheesecake sits on a white plate placed on a white marbled surface. The cheesecake has four visible layers: the bottom layer is a light brown crumbly crust, above it a thick purple blueberry layer with whole berries, followed by a thick creamy pale yellow cheesecake layer, and topped with a smooth layer of bright white cream. On top of the cream is a generous glossy purple blueberry sauce that slightly drips down the sides. The cheesecake slice is decorated with a small yellow lemon twist on top and tiny lemon zest sprinkles scattered around it and on the plate. The background is softly blurred with another slice visible. Photo taken with an iphone --ar 4:5 --v 7

Ingredients

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
3 cups Biscoff cookie crumbs

10 tablespoons unsalted butter (melted)
2/3 cup granulated sugar
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
1 stick butter (softened to room temperature)
5 oz mascarpone cheese (at room temperature)

2 1/2 cups powdered sugar
Pinch of salt

Instructions

Step 1: In a large bowl, whisk together the eggs, egg yolks, flour, superfine sugar, lemon zest, and salt until well combined. Set aside.

Step 2: Heat the heavy cream in a small saucepan over medium heat until it begins to boil. Remove from heat and stir in vanilla extract.
Step 3: Slowly pour one-third of the hot cream into the egg mixture while whisking constantly to temper the eggs. Gradually add half of the remaining cream, whisking until combined, then add the rest of the cream and whisk again.
Step 4: Cover the bowl with plastic wrap and let cool on the counter for 20 minutes, then refrigerate for one hour.

Step 5: Preheat the oven to 350°F (177°C). Butter a 10-inch springform cake pan.
Step 6: In a food processor, grind Biscoff cookies into crumbs until you have 3 cups. In a medium bowl, mix the crumbs with melted butter and granulated sugar using a rubber spatula until combined.
Step 7: Press the crust mixture firmly into the bottom and slightly up the sides of the prepared pan. Bake for 7 minutes to pre-bake the crust.

Step 8: Butter the edges of the pan, then layer 1 3/4 cups blueberries over the baked crust.
Step 9: Pour the chilled custard filling over the blueberries and bake for 50 minutes, until the top is golden brown.
Step 10: Remove the cake from the oven and let cool completely on a wire rack.

Step 11: For the blueberry sauce, combine 6 cups blueberries, water, and sugar in a saucepan over medium heat. Stir frequently and bring to a low boil without crushing the berries.
Step 12: Mix cornstarch and cold water to make a slurry, then slowly stir it into the blueberry mixture. Simmer until thickened, about 10 minutes. Remove from heat and stir in vanilla extract. Let cool completely.
Step 13: To make the mascarpone lemon buttercream, beat softened butter and mascarpone in a mixer until smooth. Gradually add powdered sugar, lemon zest, and a pinch of salt, beating until combined.

Step 14: If frosting is too thick, add heavy cream one tablespoon at a time until desired consistency is reached.
Step 15: Spread the buttercream over the cooled cake and drizzle the cooled blueberry sauce on top before serving.

Tips & Variations

Use superfine caster sugar for a smoother custard texture; if unavailable, pulse granulated sugar in a blender briefly.

Freeze blueberries in advance for the sauce if fresh berries are out of season.
Chill the crust for 2 hours if you prefer to make this a no-bake dessert.
Leftover blueberry sauce can be kept for pancakes or yogurt topping.

Storage

Store the cake covered in the refrigerator for up to 3 days. Keep the blueberry sauce separate until ready to serve. Reheat the sauce gently on the stove if needed, and bring the cake to room temperature before serving for best texture.

How to Serve

A close-up of a square slice of cake showing four clear layers: the bottom layer is a light brown crumbly crust, the second layer is dark purple blueberry pieces mixed in a creamy base, the third layer is a thick, pale creamy cheesecake, topped by a smooth, glossy deep purple blueberry sauce that drips slightly down the sides, sprinkled with small bits of bright yellow lemon zest and a thin yellow lemon slice on top. The cake is placed on a white plate with yellow lemon zest scattered around, set against a white marbled texture background. Photo taken with an iphone --ar 4:5 --v 7

Serve this delicious recipe with your favorite sides.

FAQs

Can I use frozen blueberries for the cake filling?

Yes, frozen blueberries can be used. Just thaw and drain them to prevent excess moisture from affecting the crust and custard.

How do I prevent the custard from curdling while mixing?

Temper the eggs by slowly adding the hot cream in small portions while constantly whisking. This gradual increase in temperature prevents the eggs from cooking too quickly.