1. Melt the butter in a saucepan over medium heat.
2. Add the flour and mix well to form a roux. Cook for 1 to 2 minutes, stirring constantly.
3. Gradually add the milk while whisking to avoid lumps. Allow to thicken slightly.
4. Add the double cream and mix until the texture is smooth.
5. Reduce heat to low and stir in grated cheddar cheese, a handful at a time, stirring until completely melted.
6. Season with salt, pepper and paprika if using. Mix well.
7. Serve immediately with hot chips or other snacks.