Preheat the oven to 180 °C. Whisk butter, sugar and vanilla. Add eggs, zest and juice of half a lemon and yogurt and keep whisking. Add flour, poppyseeds and baking powder and whisk.
Grease your muffin tin and dust with flour. Pour the batter into the muffin tin and bake for 25 minutes. Let them cool.
In the meantime, prep the frosting: Whisk all of the ingredients until creamy and put in a piping bag. Put some of the lemon zest aside for decoration.
Pipe the frosting on to the muffins and decorate with the remaining lemon zest.
Tipps
You can also add small lemon-fillets on top of the cupcakes instead of just zest.