Heat a large sauté pan and add the olive oil. Over medium heat, saute the onions for 2-3 minutes until they begin to color slightly. Add the fennel and garlic and cook for another 3 minutes.
Add the tomato paste and cook for one minute, then add the diced tomatoes and dried herbs and stir to combine. Bring to a simmer and turn off the heat.
Place the cut raw carrots and potatoes into the bottom of the slow cooker.
Lay the chicken thighs and then the breasts on top of the vegetables.
Next, add the beans and top with the tomato vegetable mixture from the saute pan.
Use a long wooden spoon to move the ingredients a bit to make sure some of the liquid reaches the bottom of the pot. Place the lid on and turn the heat onto low.
Cook for 6-7 hours on low. After 6 hours check the carrots and potatoes which should be fork-tender. If they aren't ready, allow it to cook a little longer. Take care not to stir the pot too much or the beans will get smashed and the chicken pieces will fall apart.
Before serving, taste and season with salt and pepper. A garnish of fresh herbs such as basil adds a bright and fresh flavor.