Some muffin batters are very high in sugar, which can caramelize during the baking and stick to the liners or the muffin tin. If the batter is also low in fat, it tends to stick to the cases more than the muffin batters with higher fat content. This recipe is relatively low in sugar and it uses oil as well as buttermilk, the combination of which should not cause any problems with the batter sticking to the paper cases.