Slow cookers are magical. The aroma of food slowly cooking fills the house, welcoming you home. I still remember my first Crock-Pot. My mom gave it to me after I graduated and moved into a small apartment. I quickly made it my most-used appliance. Add ingredients, set it to low, and eight hours later, a meal awaits.

But not everything works well in a slow cooker. I learned this the hard way while making beef stew. Fresh herbs and crumbled bacon went in early. I imagined a rich, aromatic stew. Instead, I ended up with a gray, bland, slightly bitter mess.

Here’s what I discovered: some foods simply don’t survive the slow cooking process.

Dairy: Skip the Milk and Cream
Dairy products like milk, cream, and cheese often curdle when left in a slow cooker too long. Long cooking times separate the liquids, leaving a watery, unappetizing mess. If a recipe requires dairy, add it near the end of cooking.