Start by adding the olive oil and bacon into a large saucepan over a low/medium heat. Gently fry until the bacon is nice and crispy, for around 8 minutes.
After this time, remove the bacon from the pan, leaving oil/rendered fat in the pan. Add the diced carrot, celery, onion and mushrooms. Season with a generous pinch of salt and pepper and fry over a medium heat until all of the moisture has cooked off. This will take about 6 minutes.
Next, add the garlic, chicken mince and tomato puree into the pan. Cook for about 3 minutes before adding all of the liquids (the chopped tomatoes, milk and beef stock) and bacon back into the pan.
Add the Worcester sauce, fennel seeds, Italian seasoning, salt and pepper. Stir to combine and reduce the heat to low. Leave uncovered for an hour if you have time, but cook for a minimum of 45 mins!
After this time, cook your spaghetti according to the packet instructions. Serve a portion of spaghetti with a ladle of rich chicken bolognese. Finish with a crack of black pepper, optional parmesan and dive in! This is a double batch of bolognese so if you're stirring the spaghetti into the pan with the bolognese, remember to remove half of the bolognese before doing so!