In a large frying pan, heat 1 tablespoon of olive oil over medium high heat. Add the onion, carrot, celery, garlic, jalapeno and a pinch of salt to the pan and saute until softened, about 5-7 minutes.
Add the sauteed veggies to the bowl of a large (5.6L or 6 quart) slow cooker along with the diced potatoes, corn kernels and chicken stock.
In the pan you sauteed the veggies in, add the remaining tablespoon of olive oil and sear the chicken thighs over medium high heat until golden brown on both sides. This should take 2-3 minutes per side. Once golden, add the chicken thighs to the slow cooker.
Cook on high for 3-4 hours or low for 6-7 hours.
Once the cooking time has elapsed, remove the chicken thighs from the slow cooker using tongs or a slotted spoon. Shred the meat using two forks. Set aside.
Remove 4 cups (1 litre) of the chowder from the slow cooker and carefully blend until smooth. Take care with this step as the liquid will be very hot! Pour the blended liquid back into the bowl of the slow cooker and stir to combine.
Return the shredded chicken to the slow cooker along with the grated and squeezed courgette/zucchini and the double/heavy cream. Replace the lid of the slow cooker and continue to heat on high for 10 minutes.
Season to taste with salt and pepper and serve.
If you're in a hurry, you can skip the step of sauteing the diced veggies and browning the chicken. The recipe will still work, but I highly recommend this step as it improves the flavour of the chowder. If corn on the cob is out of season, use frozen corn but make sure to defrost it before using to ensure the slow cooker heats up correctly. If using unsalted chicken stock, add 1 teaspoon of salt to begin with and season to taste at the end. Substitute chicken breast if you prefer. If you don't have or want to use a freestanding blender, you could try using a stick blender to roughly (but not completely) blend the soup at the end. You can leave out the grated courgette/zucchini if liked, but it does help to thicken the chowder at the end and is a great way to add extra veggies! Feel free to leave out the double/heavy cream if preferred or use a dairy free alternative.