Preheat the oven to 180 degrees Celsius.
In a mixing bowl, cream together the butter and sugar until light and fluffy.
Add the eggs one at a time, beating well after each addition.
Mix in the vanilla syrup.
In a separate bowl, whisk together the flour and yeast.
Gradually add the flour mixture to the butter mixture, alternating with the milk.
Pour the batter into cupcake liners.
Bake for 20-25 minutes or until a toothpick inserted into the center comes out clean.
Let the cupcakes cool before frosting.
