1Preheat the oven to 325 degrees. Lightly grease an 8-inch round cake tin.
2Sift the flour, baking powder and baking soda into a large bowl and use a hand-held whisk to combine well.
3Using an electric mixer, beat the butter and sugar until light and fluffy. Add the eggs, one at a time, to the butter mixture and beat well after each addition, scraping down the side of the bowl occasionally. Add the vanilla, lemon zest and salt and beat until just combined. With the mixer on low speed, add the flour mixture and yoghurt alternately and beat until just combined. Do not over beat. Add the lemon juice and mix until just combined.
4Pour the batter into the prepared tin and smooth the top. Bake for 40-45 minutes or until golden and a skewer inserted into the center of the cake comes out clean. Let the cake stand in the tin for 10 minutes, then turn out and transfer to a wire rack to cool completely.
1In a stand mixer fitted with the paddle attachment, cream the butter. Start with the mixer at the lowest speed, then gradually increase the speed, using a rubber spatula to scrape the bowl as needed, until the butter is light in color, is perfectly smooth, and makes a slapping sound as it hits the sides of the bowl. This should only take 30 seconds, but if the butter is cool, it can take a couple of minutes.
2Add the sugar, 1 cup at a time, and mix at the lowest speed until it’s fully incorporated before adding the next cup. When all the sugar has been added, scrape the paddle and the bottom and sides of the bowl. Add the vanilla and salt, and beat at low speed for 15 seconds. Increase the speed to as high as you can without making a mess, and whip the buttercream until it is perfectly smooth, creamy, and light, about 5 minutes. Stop the mixer once or twice to scrape the bowl and paddle, then continue beating. At first the buttercream will appear to soften, then it will stiffen and increase in volume.
3Use right away, or store in an airtight container for up to a week in the refrigerator. When you’re ready to use it, let the buttercream come to room temperature, then put it back in the stand mixer and use the paddle attachment to beat it until it’s creamy and stiff again.
1Layer each round with strawberry jam in between and top with vanilla buttercream. Cut slots with icing spatula and insert royal icing decorated sugar cookie ears.