Over the past year, people have occasionally asked on Instagram whether I sell my baked goods. My usual reply was, “LOL I’m just a home baker.” That remained true—until a few weeks ago, when someone messaged me asking if I would make cakes for a baby shower. For whatever reason—maybe it was the clear date, maybe the person’s taste matched mine—I said yes. That led to my first baking “commission”: two cakes.
The first cake I proposed was a lemon rosemary olive oil cake, even though I hadn’t made it before and didn’t have a ready recipe. The client mentioned she liked olive oil cakes and shared inspiration photos: a naked-style layer cake adorned with rosemary, blackberries, and figs. I was already enjoying a blackberry curd phase, so I suggested a lemon rosemary olive oil cake filled with blackberry curd and finished with mascarpone buttercream. She said yes—so I set about developing the cake.
I adapted a lemon olive oil cake recipe by Chelsweets. Her recipe makes a 6-inch, 3-layer cake; I doubled the quantities and baked an 8-inch, three-layer cake to serve more people for a 20-person shower. The result was quite large—if you have limited fridge space or prefer smaller batches, halve the quantities and make the 6-inch version instead.
I was anxious about serving a flavor profile that leans herbal—rosemary and olive oil are distinctive and not everyone’s favorite—but the responses at the shower were encouraging. People seemed to enjoy the cake, and I hope you will too.
A few quick notes before the recipe:
- Use a high-quality, fruity extra-virgin olive oil and taste it first. The olive oil flavor is prominent and should complement the other components.
- The blackberry curd makes just enough to fill a three-layer, 8-inch cake. If you make a 6-inch cake, consider making the full amount of curd anyway—it’s worth it.
- I provide a range for the powdered sugar in the frosting because sweetness preferences vary. I prefer less-sweet desserts; increase the sugar toward the higher end if you like a sweeter buttercream.
Lemon Rosemary Olive Oil Cake with Blackberry Curd and Mascarpone Buttercream
A subtly herbal layer cake filled with sweet-tart blackberry curd and finished with a lightly sweet mascarpone buttercream. The cake layers are adapted from a Chelsweets olive oil cake; the blackberry curd is adapted from a curd-style recipe.
Ingredients
For the lemon rosemary olive oil cake layers:
- 4 large eggs, at room temperature
- 400 g granulated sugar
- 500 g all-purpose flour
- 2 tsp baking powder
- 2 tsp baking soda
- 1.5 tsp table salt or fine sea salt
- 3 medium lemons, zested and juiced
- 1.5 tbsp finely chopped fresh rosemary
- 1 1/3 to 1 1/2 cups whole milk (see instructions)
- 1 1/3 cup extra-virgin olive oil
For the blackberry curd:
- 170 g fresh blackberries
- 1 large egg
- 2 large egg yolks
- 75 g unsalted butter, room temperature, cut into pats
- 100 g granulated sugar
- 1 tbsp cornstarch
- juice of half a lemon
For the mascarpone buttercream:
- 6 oz unsalted butter, room temperature
- 12 oz mascarpone cheese, room temperature
- 250-300 g powdered sugar (adjust to taste)
- zest of half a lemon
- 1 tsp lemon juice
To decorate:
- fresh blackberries and rosemary sprigs
Instructions
Make the blackberry curd:
- Rinse the blackberries, microwave on high for 1 minute in a microwave-safe bowl, then mash with a fork. Press the mashed berries through a sieve to yield about 1/2 cup blackberry juice.
- Measure the cornstarch and lemon juice so you can combine them quickly later.
- In a small heavy-bottomed saucepan, whisk together the egg, egg yolks, sugar, and blackberry juice. Place over low heat, add the butter, and whisk constantly until the mixture thickens and is steaming—about 160–170°F (6–12 minutes).
- Whisk the cornstarch and lemon juice together into a slurry and add to the saucepan. Continue whisking until the curd thickens substantially—about 185°F is a good target—then remove from heat and whisk for another minute or two.
- Transfer the curd to a clean container, press plastic wrap directly on its surface, cool to room temperature, then refrigerate for at least 6 hours or overnight.
Make the cake layers:
- Position a rack in the center of the oven and preheat to 350°F.
- Grease three 8-inch cake pans, line the bottoms and sides with parchment, and grease the parchment.
- Whisk together the flour, baking powder, baking soda, and salt in a medium bowl and set aside.
- Zest and juice the lemons. You should have about 1/2 to 2/3 cup lemon juice—combine the juice with milk to make a total of 2 cups liquid.
- Whisk together the milk-lemon mixture, lemon zest, chopped rosemary, and olive oil. Set aside.
- In a stand mixer with the whisk attachment, beat the eggs and sugar on medium speed for about two minutes, until light and thick.
- Add one-third of the dry ingredients, mix until just combined, then half the olive oil mixture, mixing gently. Repeat, ending with the remaining dry ingredients. Stop the mixer while the final dry bits are almost incorporated and finish folding with a spatula.
- Divide the batter evenly among the three pans (about 605 g per pan).
- Bake for 33–37 minutes, or until a skewer inserted in the centers comes out clean. Check at 30 minutes if your oven runs hot.
- Cool in the pans for 10–20 minutes, then turn the layers out onto a wire rack to cool completely. Level the tops with a serrated knife when cool.
- Assemble and frost the cake now, or freeze layers wrapped tightly for up to 2–3 weeks.
Make the frosting:
- Beat the butter and mascarpone until light and fluffy. Add powdered sugar gradually to reach your preferred sweetness, then blend in lemon juice and zest.
Assemble the cake:
- Place one cake layer cut side up on a cake board. Pipe a ring of frosting around the edge and fill the center with half the blackberry curd.
- Place the second layer cut side down. Pipe another ring of frosting and fill the center with the remaining curd.
- Top with the final layer cut side down. Spread frosting on top and use a bench scraper or offset spatula to smooth the top and sides. For a semi-naked finish, leave a thin layer so some cake shows through.
- Decorate with fresh blackberries and rosemary sprigs.
Recipe Notes
- The Chelsweets olive oil cake is a reliable base; her resources include a helpful video demonstrating leveling cake layers and creating a semi-naked finish.
- Freezing cake layers before icing makes them easier to handle and frost: frozen layers are firmer, less crumbly, and help set the room-temperature frosting on contact.
- Rosemary is noticeable but subtle in this cake. Increase to 2 tablespoons if you prefer a stronger herbal note.
