01 - Generously grease the interior of the crockpot insert with butter to prevent sticking and ensure easy serving.
02 - Melt 2 tbsp butter in a small saucepan over medium heat. Add minced garlic and sauté until fragrant, about 1 minute. Whisk in flour and cook for 1 minute to form a roux. Gradually pour in cream and milk, whisking constantly until smooth. Bring to a gentle simmer, then remove from heat.
03 - Stir salt, pepper, and half the shredded cheddar cheese into the hot sauce until completely melted and smooth. Set aside.
04 - Arrange half the sliced potatoes in the bottom of the prepared crockpot, overlapping slices slightly. Distribute half the chopped onion evenly over potatoes, followed by half the remaining cheese. Pour half the sauce over the layer.
05 - Repeat with remaining potatoes, onion, cheese, and sauce. Sprinkle paprika evenly over the top layer for color and subtle flavor.
06 - Cover and cook on high setting for 4 hours or low setting for 7 hours, until potatoes are fork-tender and sauce is bubbling.
07 - Let the dish rest uncovered for 10 minutes to allow sauce to thicken slightly. Garnish with chopped fresh parsley before serving.