01 -
Grease the inside of the slow cooker with nonstick spray or butter to prevent sticking.
02 -
In a medium bowl, whisk together heavy cream, milk, melted butter, minced garlic, salt, pepper, and paprika until smooth.
03 -
Place half of the sliced potatoes at the bottom of the slow cooker, followed by half of the onion, and sprinkle half the cheddar and Parmesan cheeses on top.
04 -
Pour half of the cream mixture evenly over the first layer, ensuring the potatoes are well coated.
05 -
Repeat the process with the remaining potatoes, onion, cheeses, and pour the remaining cream mixture evenly on top.
06 -
Cover the slow cooker and cook on low for 6 to 7 hours, or on high for 3.5 to 4 hours, until potatoes are fork-tender and the sauce is bubbling.
07 -
Turn off the heat and let the dish rest for 10 to 15 minutes to allow the sauce to set.
08 -
Garnish with chopped parsley or chives, if desired, and serve hot.