Instructions:
1. Preheat your oven to 375°F (190°C) and grease a 9×13-inch baking dish.

2. In a large skillet, melt the butter over medium heat. Add the onions and garlic, and sauté until they become translucent and fragrant.

3. Add the sliced smoked sausage to the skillet and cook until lightly browned. Remove from heat and set aside.

4. In a small saucepan, whisk together the milk and flour until well combined. Place the saucepan over medium heat and cook, stirring constantly, until the mixture thickens and begins to simmer.

5. Add the shredded cheddar cheese to the saucepan and stir until melted and smooth. Season with salt, pepper, dried thyme, and paprika. Remove from heat.

6. Layer half of the sliced potatoes in the prepared baking dish. Spread half of the sausage mixture over the potatoes. Pour half of the cheese sauce evenly over the sausage.