Mulligatawny is a mild curry soup that is packed with unique flavors. The combination of classic chicken soup ingredients with an Indian spice mix and a hint of sweet-tart flavor that comes (surprisingly!) from apples might sound strange, but the result is truly delicious. Smarts: If you're going to have leftovers, wait to stir the rice in until just before serving.
Heat a Dutch oven over medium-high heat. Add oil and then chicken to heated oil. Saute until lightly brown and just cooked through. Set aside and return pan to heat.
Reduce heat to medium and add butter to pan. When butter melts, add onions, carrots and celery. Saute, scraping up any brown bits on the bottom of the pan, until soft, 3 to 4 minutes.
Add spice mix to vegetables and cook for 1 minute to lightly toast the spices.
Add chicken back to pan. Add stock, apples and bay leaves. Bring soup to a simmer.
Simmer for 20 minutes to let the flavors come together. (If the soup starts to boil reduce heat to a low simmer.)
Stir heavy cream and cooked rice into soup and simmer for 1 minute to heat through.