Ingredients

6 tbsp unsalted butter

8 oz mascarpone cheese

2-3 tbsp heavy whipping cream

1 cup (100g) powdered sugar

1 tsp vanilla bean paste or extract

1/4 tsp almond extract (optional)

1 tbsp water

Pinch of kosher salt

1 1/4 cup (250g) granulated sugar

Zest and juice of 1 lemon

1 cup (210g) extra virgin olive oil

3 large eggs

2 tsp vanilla bean paste or extract

3/4 cup (180g) sour cream

1/2 tsp baking soda

1/2 tsp baking powder

1/2 tsp kosher salt

1/4 cup (30g) cornstarch

1 1/2 cups (195g) all-purpose flour or gluten free baking flour

Instructions

Step 1: Fill a saucepan with a few inches of water and place over medium heat. Once simmering, place a mixing bowl over the pan, making sure the bowl does not touch the water.

Step 2: Add the butter, mascarpone, and 2 tablespoons of heavy cream to the bowl and stir until melted and smooth.

Step 3: Remove the bowl from heat and whisk in the powdered sugar, vanilla extract, almond extract (if using), water, and a pinch of kosher salt.

Step 4: Place the frosting mixture in the refrigerator to chill while preparing the cake.

Step 5: Preheat the oven to 350°F (175°C). Grease the inside of a 9-inch springform pan and line the bottom with parchment paper.

Step 6: In a large mixing bowl, combine granulated sugar and lemon zest. Rub the zest into the sugar with your fingers to release the lemon’s aroma.

Step 7: Whisk in the olive oil, followed by the eggs and vanilla extract until smooth.

Step 8: Add sour cream and lemon juice, whisking to combine evenly.

Step 9: Mix in baking soda, baking powder, kosher salt, and cornstarch until well incorporated.

Step 10: Gradually whisk in the flour until the batter is smooth.

Step 11: Pour the batter into the prepared pan and bake for 40-45 minutes, or until the edges are golden and a toothpick inserted in the center comes out clean with a few moist crumbs.

Step 12: Let the cake cool completely at room temperature or in the refrigerator.

Step 13: Remove the chilled frosting from the refrigerator. It will be liquid but cold.

Step 14: Using a hand or stand mixer with a whisk attachment, whip the frosting on high speed for 30 seconds to 1 minute until thick and creamy.

Step 15: If the frosting becomes too thin, add the remaining tablespoon of heavy cream and whip again. If it curdles, refer to troubleshooting tips.

Step 16: Spread the whipped mascarpone frosting evenly over the cooled cake and serve.

Tips & Variations

For a gluten-free version, substitute the all-purpose flour with a gluten-free baking flour blend of equal weight.

If you prefer a stronger lemon flavor, add extra lemon zest or a teaspoon of lemon extract to the batter.

Almond extract is optional but adds a lovely depth to the frosting—feel free to omit if you prefer a purer vanilla taste.

Make sure the mascarpone frosting is well chilled before whipping; this helps achieve the perfect creamy texture.

FAQs

Can I use regular vegetable oil instead of olive oil?

Olive oil adds a unique fruity and rich flavor to the cake, but you can substitute with a mild vegetable oil if needed. The texture will remain moist, but the flavor will be less distinctive.

Why did my mascarpone frosting curdle?

Curdling often happens if the mascarpone mixture is whipped too fast or if the ingredients were not properly chilled. To fix this, whip gently and ensure the frosting is cold before whipping. Adding a little extra heavy cream can help smooth it out as well.