Usually my secret to perfect cupcakes is my digital scale! If you overfill or under-fill the muffin pans you may get a cupcake with a muffin top or a shriveled sunken cupcake but if you weigh them, you’ll get it right each time.  These Biscoff cupcakes probably aren’t going to have a perfect dome because we baked the filling inside but it should bake up flat. If it sinks in the middle, it was probably under-baked or the cupcakes were overfilled. 50-55 grams per cupcake total (with the cookie butter filling).