Cook the pasta according to packet instructions.
Melt the butter in a large skillet over medium heat until foaming.
Add the garlic and cook for 1 minute until fragrant.
Stir in the tomato puree, paprika, oregano, and chilli flakes (if using). Cook for 1-2 minutes until fragrant and slightly darkened.
Reduce heat to low and add the cheddar, stirring constantly until melted and glossy, 2-3 minutes.
Add pasta water, a little at a time, and whisk to loosen the sauce until it reaches the desired consistency.
Add the cooked chicken and toss to coat, warming through for 1-2 minutes.
Tip in the drained pasta and stir to combine, loosening with more pasta water as needed.