01 - Generously grease the interior of the crockpot insert with butter to prevent sticking
02 - Melt 2 tbsp butter in a small saucepan over medium heat. Add minced garlic and sauté until fragrant, about 1 minute. Stir in flour and cook for 1 minute to form a roux. Gradually whisk in heavy cream and whole milk until smooth. Bring to a simmer, then remove from heat. Stir in salt, pepper, and half the cheddar cheese until fully melted
03 - Arrange half the sliced potatoes in the crockpot, overlapping slightly for even cooking. Distribute half the chopped onion evenly over potatoes, followed by half the remaining cheddar cheese. Pour half the cheese sauce over the layer
04 - Repeat with remaining potatoes, onion, cheese, and sauce. Sprinkle paprika evenly over the top layer for color and subtle flavor
05 - Cover and cook on high setting for 4 hours or low setting for 7 hours, until potatoes are completely tender when pierced with a fork
06 - Remove lid and let stand for 10 minutes to allow sauce to thicken slightly. Garnish with chopped fresh parsley before serving