Preheat oven to 375°F (190°C).
Cut cauliflower into florets and steam or boil until just tender, about 8-10 minutes. Drain well.
In a saucepan, melt butter over medium heat. Whisk in flour to make a roux and cook for 1-2 minutes.
Gradually whisk in milk and stir until thickened.
Add 1 cup of cheddar cheese and stir until melted. Season with salt, pepper, and paprika.
Place cauliflower in a baking dish and pour the cheese sauce over it. Top with remaining cheese.
Bake for 20-25 minutes, until golden and bubbly. Serve warm.