Sear the chicken: Heat the olive oil in a large frying pan over medium-high heat until it shimmers and you see tiny ripples across the surface. Add the chicken thighs in a single layer — you'll hear a satisfying sizzle as they hit the pan. Cook for 3-4 minutes per side until the underside turns a deep, golden brown and releases easily from the pan. Transfer the browned chicken to the slow cooker insert. The searing locks in moisture and adds a rich, savoury flavour that you simply can't get from raw chicken alone.

Sauté the aromatics: In the same pan (don't wash it — the browned bits are pure flavour), reduce the heat to medium and add the diced onion. Stir frequently for about 4 minutes until the onion turns translucent and gives off a sweet, fragrant aroma. Add the minced garlic and cook for another 30 seconds until you can smell it becoming fragrant but not burning — the garlic should soften and turn just slightly golden at the edges.

Build the sauce base: Pour in the chicken stock and use a wooden spoon to scrape up all those brown bits from the bottom of the pan — this process is called deglazing, and it infuses the sauce with incredible depth. Stir in the chopped sundried tomatoes, tomato purée, dried oregano, dried basil, salt, and pepper. Let the mixture come to a gentle simmer, which you'll see as small bubbles breaking the surface, then pour everything over the chicken in the slow cooker.

Slow cook: Cover the slow cooker with the lid and cook on low for 4-6 hours or on high for 2-3 hours. You'll know the chicken is done when it feels tender when pierced with a fork and the internal temperature reaches 74°C. The sauce will look quite thin at this stage — don't worry, we'll fix that in the next step.

Add the cream and cheese: Carefully remove the chicken thighs from the slow cooker and place them on a plate. Pour the double cream and grated Parmesan into the sauce, then stir gently until the cheese has fully melted and the sauce takes on a smooth, velvety texture. The colour will shift from a reddish-brown to a warm, creamy orange, and the aroma will become noticeably richer and more indulgent.

Thicken the sauce (optional): If you prefer a thicker sauce, whisk the cornflour and cold water mixture into the slow cooker. Replace the lid and cook on high for 15-20 minutes — you'll see the sauce visibly thicken and coat the back of a spoon. Return the chicken to the slow cooker, spoon some sauce over the top, and let everything warm through for 5 minutes.

Rest and serve: Turn off the slow cooker and let the dish sit for 5 minutes before serving. This resting time allows the sauce to settle and the chicken to reabsorb some of the liquid, resulting in juicier meat. Garnish with fresh basil leaves if you have them, then serve over pasta, rice, or mashed potatoes.