Sauté the Chicken: Heat the olive oil in a large, heavy-bottomed pot or Dutch oven over medium-high heat until it shimmers. Add the cubed chicken and sear until golden brown on all sides, about 5-7 minutes. You'll notice the pieces turning from a raw pink to a lovely caramelised hue. Remove the chicken with a slotted spoon and set aside, leaving any rendered juices in the pot.

Build the Aromatic Base: Reduce the heat to medium. Add the chopped onion, carrots, and celery to the pot. Sauté for 8-10 minutes, stirring occasionally, until the vegetables soften and the onion becomes translucent and fragrant. You'll hear a gentle sizzling and smell their sweetness developing. Add the minced garlic and cook for another minute until it becomes aromatic but not browned.

Create the Roux: Push the vegetables to one side of the pot. Add the butter to the empty side and let it melt. Once melted, sprinkle in the plain flour, stirring constantly with a wooden spoon for 1-2 minutes to form a paste (this is your roux). It will smell nutty and turn a pale golden colour. Gradually whisk in the chicken stock, a little at a time, ensuring no lumps form, until the mixture is smooth and begins to thicken slightly.

Simmer the Stew: Return the seared chicken to the pot. Stir in the milk, dried thyme, and dried sage. Season generously with salt and freshly ground black pepper. Bring the mixture to a gentle simmer, then reduce the heat to low, cover, and cook for 15 minutes. The aroma will fill your kitchen, and the stew will be visibly bubbling softly.

Prepare the Dumplings: While the stew simmers, prepare the dumplings. In a large mixing bowl, whisk together the plain flour, baking powder, and salt. Add the cold cubed butter and rub it into the flour mixture with your fingertips until it resembles coarse breadcrumbs. Gradually add the milk, mixing with a fork until a soft, shaggy dough forms. Be careful not to overmix; a slightly lumpy texture is fine.

Cook the Dumplings: Uncover the simmering stew. Drop spoonfuls of the dumpling dough directly into the hot liquid. Don't worry if they look a bit rustic – that's part of their charm! Ensure they are mostly submerged but not overcrowded. Cover the pot tightly again and cook for 15-20 minutes without lifting the lid. The dumplings will puff up significantly, becoming pillowy and tender. A skewer inserted into a dumpling should come out clean.

Finish and Serve: Once the dumplings are cooked, remove the pot from the heat. Let it rest for 5 minutes, allowing the flavours to meld beautifully and the stew to thicken further. Give it a final taste and adjust seasoning if needed. Ladle generous portions into bowls, garnishing with fresh chopped parsley. The stew will be thick and creamy, the chicken tender, and the dumplings wonderfully light.