For the muffins with liquid Toffifee center, mix the soft butter with egg, sugar, hazelnut cream, flour and baking soda until smooth.
Pour the batter into a muffin tin and place a piece of Toffifee in the center of each muffin tin.
Bake the muffins with liquid Toffifee center in the oven at 160 °C hot air for about 15 – 20 minutes.