1. Prepare the Cake Pans:

Preheat the oven to 350°F (175°C).

Spray two 8-inch round cake pans with baking spray with flour. (Alternatively, butter and flour the pans.)

Line the bottoms of the pans with circles of parchment paper.  

 

Spray (or butter) the parchment paper as well.

2. Combine Dry Ingredients (Cake):

In a medium bowl, whisk together the flour, baking powder, baking soda, and kosher salt.

3. Combine Wet Ingredients (Cake):

In a large bowl, whisk together the granulated sugar, melted butter, vegetable oil, and lemon zest until combined.

Whisk in the eggs, one at a time, until lightened in color, about 1 minute.

Whisk in the buttermilk, lemon juice, and vanilla extract until well combined.

4. Combine Wet and Dry Ingredients:

Add the flour mixture to the wet ingredients in 3 parts.

Whisking to combine after each addition. Be careful not to overmix.

5. Bake the Cake:

Evenly divide the batter between the prepared cake pans.

Tap the pans a few times on a kitchen towel on your countertop to level the surface and remove any large air bubbles.

Bake until a toothpick inserted in the center comes out with only a few moist crumbs, 30 to 35 minutes.

6. Cool the Cake:

Transfer the cake pans to a cooling rack.

Let the cakes cool in the pans for 10 minutes.

Then, carefully turn the cakes out onto a cooling rack to cool completely, about 1 ½ hours.

7. Make the Jam Filling:

While the cake is cooling, make the jam filling.

In a small bowl, whisk together the cornstarch and 1 tablespoon of water until smooth.

In a small saucepan, heat the raspberry jam over medium heat until pourable and smooth, about 1 minute.

Remove the jam from the heat. Whisk in the cornstarch mixture.

Return the saucepan to medium heat. Bring the mixture to a boil.

Boil, stirring constantly, until no longer cloudy with cornstarch and a rubber spatula dragged through the mixture reveals the bottom of the pan for a few seconds before the jam flows back together, 2 to 3 minutes. This means the jam is thickened.

Transfer the thickened jam mixture to a bowl and let it cool completely.

8. Make the Raspberry Frosting:

To the bowl of a stand mixer fitted with the paddle attachment (or using a hand mixer), add the softened butter.

Beat on medium speed until smooth, about 1 minute.

Scrape down the bottom and sides of the bowl.

Add the raspberry jam, lemon juice, and vanilla extract. Beat on low speed until just combined, about 30 seconds. The mixture might appear broken (separated) at this point, but that’s okay.

Increase the speed to medium and beat until the butter and jam are no longer separated, 1 to 2 minutes.

Gradually add the powdered sugar. Beat on low speed until combined.  

 

Scrape the bottom and sides of the bowl.

Increase the speed to medium and beat until the frosting is smooth and fluffy, 3 to 4 minutes.

9. Assemble the Cake (Crumb Coat):

Once the cake layers are completely cool, place one cake layer on a cake plate or serving stand.

Spread about ½ cup of the raspberry frosting over the top of the cake layer. This will be a thin “crumb coat” to seal in any loose crumbs and prevent them from getting into the final frosting.

Spoon about ½ cup of the frosting into a zip-top bag. Cut a ¾-inch opening in one corner of the bag. (Alternatively, use a pastry bag fitted with a ¾-inch tip.)

Pipe a thick border of frosting around the edge of the frosted cake layer. This will create a barrier to prevent the jam filling from leaking out the sides of the cake.

10. Add the Jam Filling:

Stir the cooled jam filling to loosen it up, if needed.

Spread the jam filling on top of the cake within the frosting border. Leaving about ½ inch of space between the filling and the border.

11. Add the Second Cake Layer:

Carefully top with the second cake layer.

12. Frost the Cake (Final Coat): Spread about 1 cup of the frosting in a thin layer over the top and sides of the cake. This is another crumb coat.

Chill the cake, uncovered, in the refrigerator for 30 minutes or in the freezer for 10 minutes to set the frosting and the filling. This will help to create a smooth, even finish.  

 

Use the remaining frosting to frost the top and sides of the cake.

13. Decorate and Serve:

Decorate the cake with fresh raspberries, if desired, or serve them on the side.

Slice and serve. Enjoy!