This lemon blackberry cake has a tender, buttermilk lemon poppy seed cake base, soaked with a lemon simple syrup, a fresh blackberry buttercream in between the layers, and coated with a tangy lemon cream cheese frosting.
3tablespoonspoppy seedssoaked in hot water first (see notes)
1 (225g) cupof butterroom temperature
4tablespoonslemon zest (about 4 large lemons)
1 ¼cupsbuttermilk
5egg large whites
Lemon Syrup:
½ cupfresh lemon juice (juice of about 2 large lemons)
¼ (50 grams) cupgranulated sugar
Lemon Cream Cheese Frosting:
10tablespoons(5 ounces) cream cheese, room temperature
1 ½ (338 grams)cupsbutterroom temperature
6-7 (750-875 grams) cupspowdered sugar
⅛teaspoonsalt
½teaspoonvanilla
1teaspoonlemon extract
1tablespoonlemon zest (zest of about 1 large lemon)
Blackberry Buttercream Frosting:
1cupblackberries
2tablespoonslemon juice (juice of about ½ a large lemon)
1 (225g) cupbutterroom temperature
4 (500 grams) cupspowdered sugar
1tablespoonlemon zest (the zest of about 1 large lemon)
⅛teaspoonsalt
Instructions
Cake:
Soak your poppy seeds in hot water for 1 hour.Drain off water using paper towels or a dish cloth so you don’t lose any seeds.
Preheat oven to 350 degrees Fahrenheit. Line either three 8-inch pans OR four 6-inch pans with parchment paper AND grease.
In a large bowl or stand mixer combine flour, sugar, baking powder, salt, and lemon zest, mix together so that there are no lumps.
Cut butter into small chunks and add into dry ingredients.Use a stand mixer or hand mixer and mix until the dry ingredients resembles sand. Then whip on high for 1 minute to aerate the butter.
Whisk together egg whites, buttermilk, poppy seeds, and lemon zest. Add liquid ingredients a little at time until fully incorporated into dry ingredients. Make sure you scrape down the sides of the bowl. Do not over mix. The cake batter should be smooth.
Divide the batter evenly between your lined and greased cake pans. If you are using the 8 inch pans bake for 22-28 minutes OR if you are using the 6 inch pans bake for 22-25 minutes. Start checking your cakes around 20 minutes. Insert a toothpick in the center, you should have a few moist crumbs but no batter on it. If you push on the top of the cake gently it should spring back.
Let your cakes cool in their pans for 10 minutesand then remove from their pans and let cool on cake racks. While cakes arebaking, prepare the lemon syrup.
Lemon Syrup:
While cakes are cooling prepare your lemon syrup. In a small saucepan over medium heat add lemon juice and sugar. Bring to a boil and let boil for 1 minute until the sugar is completely dissolved.
If your cakes are domed in the middle level them off so they are flat. Use a toothpick to poke small holes all over the top of the cake and generously brush the lemon syrup over the tops of the cake, trust me you'll want to use all the syrup. Let cool completely.
Blackberry Buttercream:
In a small sauce pan over medium heat add your blackberries and lemon juice. Stir constantly until blackberries begin to soften. Mash them as you stir with your spoon. Cook for 5-7 minutes until you have a thick jammy mixture.
Place your blackberry mixture and softened butter into a food processor or a high speed blender and blend together until smooth. This will get rid of most of the seeds. Cool butter and jam mixture.
If you don’t have a high-speed blender or food processor you can push the jam through a mesh strainer and then cool it before creaming the jam and butter together.
Once cool beat your blackberry butter until light and fluffy. Add in 1 cup of powdered sugar, salt, and lemon zest and beat. Slowly add in the remaining powdered sugar and cream together until smooth and fluffy.
Lemon Cream Cheese Frosting;
Beat butter and cream cheese together until fluffy.Add in 1 cup of powdered sugar, vanilla, lemon extract, and salt and cream together.
Add in the remaining powdered sugar, 1 cup at atime, until smooth and fluffy.
Cake Assembly:
Place 1 cake layer bottom side down on your cake plate. Spread a very thin layer of lemon cream cheese frosting over the top of the cake. Then spread about ½-¾ cup of blackberry buttercream over top. Make sure the frosting is super level. Repeat for the next 1-2 layers.
Place your final cake layer bottom side up so you have a nice flat cake for your top layer.
Cover the top and outside of the cake with a thin layer of the lemon cream cheese frosting to act as a crumb coat. Place entire cake in the freezer for 15 minutes or in the fridge for 30 minutes. Once chilled completely frost the cake. Top with fresh blackberries if desired.
Notes
Soak Poppy Seeds. Pour hot water over the poppy seeds and let soak for one hour before using. This will help make sure your poppy seeds don’t absorb too much moisture from the cake.Serving. This cake is best served at room temperature. If served cold the cake can seem dry and dense.Why is my lemon cake dry?If your lemon cake is dry, there’s a chance you either overmixed the batter, leading to gluten development resulting in a tough cake OR that the cake is overbaked.How do I increase the flavor of my lemon cake?If you want to make your cake extra lemon-y you can add an extra tablespoon of lemon zest or 1 teaspoon of lemon extract.Can I make the lemon cream cheese frosting a lemon buttercream?The tang in the cream cheese frosting really helps balance out the flavors of this sweet cake. However, if you’d like make this a lemon buttercream frosting instead, you can replace the cream cheese with an equal amount of room temperature butter.Storage TipsStoring the Cake in the Refrigerator & Room TemperatureThis cake is fine to sit out at room temperature for several hours. However, it should be stored overnight or for long periods of time in the refrigerator. If the cake has been cut, wrap any exposed areas in plastic wrap to prevent the cake from drying out. Let the cake come to room temperature before eating. This cake is best eaten within 3 days.Freezing a Cake WholeIf you have the room in your freezer you can freeze an entire frosted and decorated cake whole! I recommend chilling the cake so the frosting is solid, then wrapping the cake tightly in 2-3 layers of plastic wrap to prevent any freezer burn. You can store the whole cake in the freezer for up to 3 months. To thaw, unwrap the cake and let come to room temperature by thawing on the counter.Freezing individual slicesOne of my favorite ways to store leftover cake is to freeze individual slices! Slice the cake and wrap each slice in plastic wrap. Then store in a plastic Tupperware container in the freezer. It’s easy to pop out one slice whenever you have a craving, just unwrap the individual slice, thaw, and enjoy.