Butter Cake with Blackberry Filling and Lemon Russian Buttercream

The thing I look forward to most about my birthday is cake. To my mom’s horror, I’ve made my own cake for years. I think she’s warmed up to the action because I always assure her I get exactly what I want.

For almost a year I decided I would go with an old standby of Bonnie Butter Cake with chocolate icing. At the 11th hour I decided I wanted something different. Who knows why because I had nothing else in mind. I brainstormed ideas with my sister who humors my craziness. Out of the session we came up with two great ideas: 1) will be a cake for My Armo (can’t tell you what it is quite yet) 2) a cake for me that met all the checkboxes I didn’t know existed.

Sister enlightened me with Russian buttercream, something I never heard of and is made with condensed milk and butter. We paired it with my favorite standby Bonnie Butter Cake and made it “summery special” with blackberry filling.

I’ve made two of the components plenty of times so I know you’ll have good results. I followed the Russian Buttercream recipe from Sugarologie almost exactly (I added lemon zest) so I’m confident it will work for you as well.

Blackberry Filling Ingredients
24 ounces blackberries
⅔ c sugar
⅛ tsp salt

Blackberry Filling Directions
Put 24 ounces blackberries, ⅔ c sugar, ⅛ tsp salt into a saucepan and boil. Reduce to a simmer. When the liquid is almost gone (around 45 minutes), test its doneness on a plate. Add a tiny bit to a plate, if it solidifies, it’s finished.

Turn off the heat. When it’s cooled to room temperature it should be solid and when you scoop out of it, nothing should bleed into the hole.

Notes
You can use this basic recipe for most fruit, but will need to adjust the sugar. For example, blueberries are sweeter so you’ll need less sugar.

If you’re wanting it to be a preserve, don’t cook it quite as long. I don’t make it to be shelf stable so you’ll need a different recipe for that.

Lemon Russian Buttercream Ingredients
1 ½ c of butter
⅛ tsp salt
1 Tbl lemon zest
8 ounces condensed milk

Lemon Russian Buttercream Directions
Add 1 ½ c of room temperature butter (should be able to make a slight indent with your finger when pressed) to a bowl. Add ⅛ tsp salt and 1 Tbl lemon zest. If you have a stand mixer, use the whisk attachment. Beat until the butter is light and fluffy.

Drizzle in ⅓ c of condensed milk and beat until incorporated. Repeat two more times. It should be smooth and silky.

Notes
I’ve read that condensed milk and butter should be the same temperature or you risk the icing breaking. I put the butter and milk in the refrigerator. I took them out at the same time. Scientifically, they will not warm at the same rate. Functionally, it did the trick.

My butter did get a tad too soft while mixing so I popped the bowl in the fridge for about 10 minutes and continued on. Worked like a charm. In full disclosure, I think the perfect indoor temperature is 80 degrees so you might not have that problem.

Bonnie Butter Cake (a Betty Crocker Masterpiece) Ingredients
2 ¾ c all-purpose flour
1 ¾ c sugar
2 ½ tsp baking powder
1 tsp salt
2/3 c butter, softened
1 ¼ c milk
2 eggs
1 1/2 tsp vanilla

Bonnie Butter Cake Directions
Heat oven to 350. Line two 9” round pans with parchment paper and give a quick swipe of butter around the rim.

Use an electric mixer on low speed to incorporate 2 ¾ c flour, 1 ¾ c sugar, 2 ½ tsp baking powder, and 1 tsp salt in a large bowl.

Cut 2/3 c softened butter into roughly 1/3 Tbl pieces. Your finger should be able to make an indent in the butter with some resistance. If the butter is too cold, it’ll be hard to mix. Butter too warm won’t hold a lift as well. Scatter the cut butter in the bowl. Mix on low until the butter is pea size.

Measure 1 ¼ c milk into a 2 c liquid measure cup or small pot with a pour spout. Add the 2 eggs and 1 1/2 tsp vanilla to the milk and give it a quick whisk to combine.

Add all but ½ c of the milk mixture to the flour. Begin mixing on low speed until a batter begins to form. Beat on medium-high for about 60 seconds. It should be light and fluffy. Reduce speed to medium-low and drizzle in the remaining milk. Beat for about 45 seconds. It might look a little lumpy.

Pour the batter evenly into two cake pans and smooth the top with a spatula. Pick up the pan about 2 inches from the counter and drop it. Repeat twice. Pop it in the oven and bake for 25-3 minutes. Look for a light brown color and a few crumbs on a toothpick after it’s inserted into the middle of the cake. Allow to cool for 10 minutes. Flip it over on a cooling rack and allow to cool completely.

Notes
I adjusted the order of the mixing ingredients for the original recipe.

If you’re wanting a bakery style cake,you can use 3 c of flour in place of the AP flour. After it bakes, you would cut off the dome of the cake to make it a flat top. You can either munch on the scraps or turn them into cake balls. The dome doesn’t bother me so I don’t bother with that step.

To Assemble
Put a cake layer upside down on a cake platter or large plate. Swipe a thin layer (the thinnest you can) of buttercream on the layer. Add ¾ of the blackberry filling on top of the icing and spread it, leaving about a 1/2 “ rim of nothing. If your filling isn’t thick enough, you can pipe a rim of buttercream to hold it in black.

Add the second layer of cake right side up on top of the black berry. Use a butter knife (I don’t own an offset spatula because I wouldn’t use it enough) and fill in the space between the layers with buttercream.

Add butter cream to the sides and top. My cake decorating skills are basic so after the icing is on even, I hold a knife at about a 45 degree angle and make swirls.

Notes
There’s a sweet spot for your icing temperature. If it’s too cold it won’t spread easily. If it’s too warm, it will slide around. My icing was too warm, but I was in a time crunch so I rolled with it.