Dessert, Food & Drink

Chocolate Olive Oil Cake with Rosemary Buttercream

Crafts and a Cat | Chocolate Olive Cake with Rosemary Buttercream by Kayleigh KosmasMy first post of the year is one I promised way back in 2016. I meant to write it up sooner but got busy with the holidays and work and before I knew it the year had disappeared on me. There’s never a wrong time for cake though, and I promise this one is worth the wait! I am by no means an expert baker, but there are a couple desserts I’ve made over and over again, experimenting with temperature and ratios with obsessive attention to detail until they are perfect. This chocolate olive oil cake with rosemary buttercream is one of them. The first time I made it, it was a humble loaf cake with lumpy buttercream slathered on top. As I’ve refined the recipe and learned baking lessons by making mistakes (always sift powdered sugar before dumping it into creamed butter!), it’s matured into a simple but elegant layer cake that’s a family favorite for holidays, birthdays and just because. The one pictured here was my family’s Thanksgiving dessert.

Crafts and a Cat | Chocolate Olive Cake with Rosemary Buttercream by Kayleigh Kosmas

The cake itself has no butter; olive oil and just enough sugar and a splash of apple cider make it rich, moist and not overly sweet. The buttercream is infused with fresh sprigs of rosemary and is an earthy, herbal contrast to the chocolate cake. If you saw last week’s post you already know how fond I am of rosemary, especially in sweet incarnations. I’ve made this cake throughout the year, and no matter when you eat it, it seems perfectly seasonal; maybe it’s because there’s fresh rosemary in the garden all year, or because chocolate never goes out of style. I’ll make it again next month for P’s birthday; he’s requested it for the past few years and I’m happy to oblige. When I bake it, I get to eat it too, after all. Trust me, this is one you want to save for your next occasion.Crafts and a Cat | Chocolate Olive Cake with Rosemary Buttercream by Kayleigh Kosmas Crafts and a Cat | Chocolate Olive Cake with Rosemary Buttercream by Kayleigh Kosmas

Chocolate Olive Oil Cake with Rosemary Buttercream

Prep Time 40 minutes
Cook Time 40 minutes
Total Time 1 hour 30 minutes


For the cake

  • 3 cups flour
  • 1 1/2 cups unsweetened cocoa powder
  • 3 1/4 cups sugar
  • 2 1/2 tsp salt
  • 1 tsp baking soda
  • 1 tsp baking powder
  • 2 2/3 cup olive oil
  • 2 1/2 cup milk
  • 5 eggs room temperature
  • 3/4 cup apple cider

For the rosemary buttercream

  • 2 cups butter
  • 2-3 cups confectioners sugar
  • 2-3 Tbs. milk
  • pinch salt
  • 5-6 sprigs of rosemary


For the cake

  1. Preheat the oven to 325º Fahrenheit.
  2. Sift together the dry ingredients in one bowl, and mix the wet ingredients in a larger one. Slowly add the dry ingredients to the wet, mixing until just blended.
  3. Divide the batter evenly among three greased, 8" cake pans. Whack the pans on the counter to eliminate air bubbles. Bake until a toothpick inserted in the middle comes out clean; start checking around 30 minutes.
  4. Let cakes stand for 5-10 minutes, then turn onto a rack to cool.

For the rosemary buttercream

  1. Melt the butter over medium-low heat along with the rosemary. Bring it to a simmer and remove from heat after a couple minutes, before the butter starts to brown. Let the rosemary sit at least 30 minutes before discarding, or as long as overnight. Place butter in the refrigerator just until opaque, about an hour; it should still be soft enough to mix.
  2. Cream the infused butter with sifted sugar and milk; start with 2 cups of sugar and 2 Tbs. milk. Add a pinch of salt, and add more sugar and milk to taste.
  3. Frost away!

Recipe Notes

I find freezing the cake layers makes them much easier to frost, but this step isn't a necessity.
Baking at a slightly lower temperature than other cake recipes call for and whacking the pans on the counter both help produce level cake layers. If yours still come out too "domed", level them with a sharp knife and nosh on the extra bits while you frost.

Crafts and a Cat | Chocolate Olive Cake with Rosemary Buttercream by Kayleigh Kosmas Crafts and a Cat | Chocolate Olive Cake with Rosemary Buttercream by Kayleigh Kosmas Crafts and a Cat | Chocolate Olive Cake with Rosemary Buttercream by Kayleigh Kosmas Crafts and a Cat | Chocolate Olive Cake with Rosemary Buttercream by Kayleigh Kosmas

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  • Reply Chloe | Conscious by Chloe January 11, 2017 at 2:47 pm

    What a beautiful cake! And I love the styling.
    Are those Mimi Ceramics plates? I’ve got the exact same ones, you’ll see them on my blog next week for a breakfast post 🙂
    I’m happy to have discovered the beautiful blog of a fellow Portlander and can’t wait to read more into your archives.
    Take care!

    – Chloe

    • Reply Kayleigh Kosmas January 11, 2017 at 8:26 pm

      Aww thanks Chloe! And yes they are, they’re some of my favorite plates!

  • Reply Marie Nelson December 11, 2017 at 7:48 am

    I have a lot of experience in the kitchen & I intend to make this cake per my daughter’s request, for her birthday. That being said, I am going to make 2 assumptions regarding the instructions. The 1st one being that it is not necessary to use an electric mixer. The 2nd, that the butter must be allowed to solidify after infusing it with the rosemary. I think that for the benefit of those with less experience, you should at least clarify(no pun intended) the issue with the butter.

    • Reply Kayleigh Kosmas December 11, 2017 at 5:06 pm

      Hi Marie,

      Thanks for your feedback! I’ve clarified the recipe. Hand mixing is just fine. 🙂 Hope your daughter loves her birthday cake!


  • Reply Marie Nelson December 17, 2017 at 1:06 pm

    Hi Kayleigh,
    I had to come back with a review of the finished cake. As I stated in an earlier comment, my daughter requested this cake for her birthday.
    I must admit that I was doubtful as to the outcome of the finished layers due to the fact that the batter was very thin. Since all I had were three 9 inch round pans I figured that I’d better check on them after 25 minutes as they would be thinner. When after 25 minutes there was absolutely no change, I was sure I’d done something wrong. After another 10 minutes there was a drastic change but we weren’t quite there. A total baking time of 40 minutes @ 325° F yielded 3 perfect layers, until I turned them out of the pans. What followed was my own fault. I learned that you should definitely not use parchment paper to line the bottom of the cake pans if not told to do so. The batter is so thin that it causes the paper to ripple resulting in batter oozing under the paper. The layers released just fine but were they ever ugly on the bottom.
    Finally. The layers have cooled & I’m doubting the savory taste of the buttercream with the cake but I plunged right in & frosted the cake. After all, my daughter did ask for this cake, it wasn’t my idea. So what if it looks like it doesn’t have enough frosting on it. My buttercream turned out a bit on the thin side, I have no idea if it was supposed to or not, how about that Kayleigh? The frosting being so thin made the layers slide around on each other. Is that why you suggested freezing the layers? I finally got what I believed was enough frosting onto the cake per the pictures you shared & after sliding the layers into position & smoothing the frosting I placed the cake in the refrigerator to set the frosting & keep everything from sliding. After it was set I added the rosemary sprigs along the edge of the top layer & also the bottom layer in opposing directions.
    Voila! The final result was a rustic but very simply pretty cake. The flavor was so amazing that it almost defies description. This chocolate cake is awesome all by itself, seriously, no frosting needed. The best chocolate cake I’ve ever eaten. The frosting is wonderful. The two components together constitute the very best frosted chocolate cake I have ever tasted. I am not a huge fan of sweets. I usually eat one slice of the birthday cake that I bake for someone out of a sense of obligation. That one slice is usually my limit. Before I finished the first slice I told my daughter that I definitely wanted at least one more slice of her cake before it was all gone.
    By the way, my daughter loves, loves, loves this cake.

    • Reply Kayleigh Kosmas December 26, 2017 at 3:19 pm

      Hi Marie, I’m SO glad the cake was such a hit! It’s truly my favorite chocolate cake in the world and it makes me so happy that others are enjoying it too. 🙂 I haven’t had issues with the consistency of the frosting in the past, but I’ll pay extra close attention to how I make it next time and maybe add some notes to the recipe. Thank you so much for taking the time to share your experience!

  • Reply Marie Nelson December 29, 2017 at 10:47 am

    Hi Kayleigh,
    I keep thinking about my frosting being so thin when I made this & the only thing I can come up with is to question whether or not you measured the sugar before or after sifting. I measured after. That would certainly result in a thinner frosting. What do you think?

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