1Combine softened butter, vanilla, and sugar in a bowl and cream them together until well mixed.
2Add plain yogurt to the creamed butter mixture and mix well until combined, ensuring no lumps of yogurt remain.
3Sift the all-purpose flour, baking powder, and salt into the mixture.
4Add milk to the mixture and mix everything well until no lumps of flour are visible, but do not overmix.
5Grease your microwave-safe mold with butter and flour, then line the bottom with parchment paper.
6Pour the cake batter into the prepared mold and use a spatula to spread it as evenly as possible.
7Pop the cake into the microwave for 5 to 8 minutes, depending on your microwave's power and the mold's material and size. Check doneness with a toothpick.
8Let the cake cool in its pan for 10 minutes, then turn it over onto a clean surface and let it cool completely.
9To make the frosting, cream together the softened butter and vanilla using a hand mixer.
10Gradually add powdered sugar to the butter and vanilla mixture, mixing until light in color and volume. You can add a splash of milk or heavy cream for a looser frosting.
11Frost the cooled cake entirely with the buttercream, smoothing out the top and cleaning the edges with a spatula or knife.
12Decorate the cake with sprinkles by sprinkling them around the top edge.
You will not taste the yogurt, it will add moisture and act as a binder, substituting eggs.
Sift the dry ingredients for a better result.
The cake might look pale because it doesn't contain eggs.
Do not overmix the cake batter.
Cooking time will vary depending on your microwave and the mold used. Check with a toothpick after 5 minutes and cook longer if needed, but do not overcook.
For the buttercream, you can add a splash of milk or heavy cream for a creamier, looser frosting.