Put potato chunks, butter, and sliced onions in the slow cooker and get a meal so delicious your family will be begging for more.

3 pounds Yukon Gold potatoes, peeled and cut into 1 1/2-inch chunks
1 medium yellow onion, thinly sliced
3 cloves garlic, minced
1/2 cup (1 stick) unsalted butter, cut into pieces
1 cup low-sodium chicken or vegetable broth
1 teaspoon kosher salt, plus more to taste
1/2 teaspoon freshly ground black pepper
1/2 teaspoon dried thyme (optional, but adds a nice herbal note)
1/2 cup whole milk or half-and-half, warmed
1/4 cup sour cream (optional, for extra creaminess)
1/4 cup chopped fresh parsley
2 green onions, thinly sliced (green parts only), for garnish