Preventing Toughness Through Proper Mixing

Overmixing is the primary cause of tough, dense cakes, especially with flour-heavy batters containing molasses or heavy syrup. 

The key is minimal mixing once flour is added - mix just until ingredients disappear. Use lowest mixer speed and scrape bowl frequently rather than mixing longer. The alternating method (dry ingredients with liquids) creates more tender results than dump-and-mix. 

Sour cream adds both moisture and acidity that tenderizes gluten strands. Room temperature ingredients combine more easily, reducing mixing time. The finished batter should look slightly rough rather than perfectly smooth - smooth batter often indicates overmixing and will produce tough cake.