Lemon Basil Fraisier Cake with Diplomat Cream

grimmsfoodietales
Jul 3
5 min read

link to reddit post and link to OP's recipe

Made June 29, 2025

Note: Serves 8-10

Trust the recipe, you may wonder if there will be enough syrup or cake batter, but it works out. I did change the syrup's directions a little, because boiling two tablespoons of water is ridiculous. I also wrote out some changes I would make to the assembly to better fit the look I'd like the cake to end up having.

If not pre-made, basil extract requires 3 days for infusing – to make, simply add a fistful of basil (or their stems) and 375 ml of mid-quality vodka to an air tight glass jar and store in a dark cool place for 3 days. Remove basil leaves before using. If basil extract is prepared but otherwise making in a single day, allow for at least 4.5 hours.

Sponges, syrup, and strawberry filling can be made up to a day ahead of time. Diplomat cream should be made in the same day the cake is assembled.

All Ingredients:

1⅓ cups Heavy Whipping Cream

2⅔ cups Full Fat Milk

Butter (for greasing pan)

9 Eggs

½ cup All Purpose Flour

½ cup Cake Flour

6g Gelatin Powder

263g Granulated White Sugar Powdered Sugar (optional, for dusting) 44g Cornstarch ½ teaspoon Baking Powder 4 teaspoons Sunflower or other Neutral Oil ¼ teaspoon Cream of Tartar ¼ teaspoon Salt

½ teaspoon Vanilla Extract 1¼ teaspoons Basil Extract

3 Lemons 2 lbs Strawberries 1 cup Basil

Lemon Basil Syrup Ingredients:

30ml (~2 tablespoons) Water

½ cup Basil

1 lemon 38g Granulated White Sugar

Lemon Basil Syrup Directions:

Bring a cup of water to boil. Meanwhile, roughly chop basil leaves and place in a small sauce pan.

Zest the lemon and set aside for diplomat cream or sponge, then juice.

Carefully measure out 2 tablespoons of boiling water and pour over basil. Allow to steep for 10 minutes.

Add lemon juice and sugar and bring the sauce pan up to medium high head, stirring until sugar dissolves. Simmer for a minute.

Remove from heat and let syrup steep for 30 minutes.

Remove basil leaves.

Lemon Genoise Sponges Ingredients:

Butter

64g All Purpose Flour

57g Cake Flour

150g Granulated White Sugar 1 teaspoon Baking Powder

¼ teaspoon Salt

4 Eggs

2 Lemons

4 teaspoons Sunflower or other Neutral Oil

6 tablespoons Water

½ teaspoon Vanilla Extract ¼ teaspoon Cream of Tartar (optional)

Lemon Genoise Sponges Directions:

Preheat oven to 350°F (175°C).

Line the bottom of two springform pans with parchment paper discs. Then grease and flour the springform ring.

In a large bowl, whisk together both flours, sugar, baking powder, and salt.

Separate all the egg yolks from the whites, adding the whites to a small bowl. Zest the lemons.

In a third bowl, whisk the egg yolks, lemon zest, oil, water, and vanilla extract until combined.

Fold liquid mixture into the flour mixture until just combined.

Whisk the egg whites on low-speed until foamy. If using, add the cream of tartar. Continue whisking on high-speed until stiff peaks form.

Gently fold egg whites into batter, careful not to deflate.

Divide the mixture evenly between the two prepared pans, and smooth out top.

Bake until the center of cake reads between 200°- 210°F (93° - 98°C) and thermometer comes out clean, approximately 25 minutes.

Let cool to room temperature and then brush the sponges with ample syrup

Strawberry Basil Filling Ingredients:

2lbs Strawberries

½ cup Basil

13g Granulated White Sugar

Strawberry Basil Filling Directions:

Wash, dry, and remove tops from all strawberries.

Locate about 10 strawberries that are most similar in height, shape, and width. Cut them each in half, from tip to base. Place the halved strawberries along the inner ring of the springform pan to make sure you have enough for the ring between the sponges.

Reserve a few strawberries to decorate the top of the cake as desired.

Coarsely chop the remaining strawberries. Chopped pieces should be small, but not so small they form a mush.

Finely chop basil and mix with sugar into strawberries.

Lemon Basil Diplomat Cream Ingredients:

2⅔ cups Full Fat Milk

1¼ teaspoons Basil Extract

½ Lemon, Zest

5 Egg Yolks 75g Granulated White Sugar

44g Cornstarch 6g Gelatin Powder

1⅓ cups Heavy Whipping Cream

Lemon Basil Diplomat Cream and Assembly Directions:

Make the crème patisserie:

Place milk, basil extract, and lemon zest (reserved from making syrup) in a small pot and heat on medium low heat until it starts to simmer

Meanwhile in a separate bowl, whisk together the egg yolks and sugar. Then add cornstarch and whisk until combined.

Once milk starts simmering, pour half of the milk mixture over the egg yolk mixture. Whisk well, and then pour that mixture into the pot with the other half of the milk mixture. Keep whisking for 30 seconds or so, until it has thickened and looks like a custard. Remove from heat.

In a small bowl, add gelatin powder and mix in just enough water to dissolve the powder. Add hydrated gelatin to crème patisserie and whisk well until dissolved/combined.

Let cool a bit, then press cling wrap onto the crème surface, to prevent a skin from forming

Chill in the fridge until room temperature (at least 20 minutes). Do not let get below room temperature!

Make the Chantilly cream:

Once the crème patisserie has reached room temperature, whip the whipping cream until it is able to form stiff peaks.

Combine crème patisserie and Chantilly cream to form Diplomat cream:

Gently fold Chantilly cream (whipped cream) into crème patisserie (custard).

Assemble the cake:

Transfer the diplomat cream into a piping bag.

Place one of the sponges onto a cake stand or serving plate.

Pipe a ½ -inch layer of cream on the sponge.

Place an unlocked springform ring around the sponge. Note: the springform pan bottom is not used here.

Make a roughly 6” tall strip of wax paper or acetate, a few inches longer than the sponge circumference

Form the wax/acetate strip into a ring with diameter large enough to surround the sponge, but small enough to fit inside the springform pan when locked. It will be a tight fit!

Place the wax/acetate ring inside the springform ring, outside the cake, and fasten the ring. The wax/acetate ring should be seated low enough to touch the serving platter surface.

Place the reserved, halved strawberries in the ring atop the cream, cut side facing outward, stem end sitting on the cream. The strawberries should be pressed firmly against the wax/acetate film, with the ring formed with as many strawberries as possible.

Pipe cream between the strawberries, and form a solid ring of cream atop them. You should have used roughly half the cream at this point and the strawberries should not be seen from inside the ring.

Spread the strawberry basil mixture on the cream, keeping it within the outer strawberry ring.

Apply the remaining cream in spiral fashion atop the strawberry mixture. Once finished, nothing but cream should be visible from the top of the cake.

Place the remaining sponge on top, soft syrup’d side facing down. Press gently to release trapped air bubbles.

Chill overnight or at least for 2 hours.

Dust cake surface with powdered sugar immediately before serving, and decorate as desired with remaining strawberry slices.

Final Notes:

All the flavors are really light and delicate, but there, it's a really great balance. But be sure to finely mince the basil in the strawberry-basil mixture so that the basil can come out more (and have a better texture).

Other assembly option: after adding the strawberry-basil mixture, place the second sponge on top, then top the cake with the remaining cream, and decorate with reserved strawberries.

Suggestion: use the left over egg whites from the crème patisserie to make a soufflé or two.