Heat the olive oil in a large pot over medium heat. Sear the chicken for 2-3 minutes per side, until golden. Transfer to a plate; the chicken will finish cooking in the broth later on, but a quick sear helps build so much flavour.

Add the butter to the same pot. Once melted, add the shallot, carrots, and celery. Sauté for 3-4 minutes, until slightly softened.

Add the garlic to the pot, along with a pinch of red pepper flakes if using, and stir for another minute until fragrant.

Pour in the white wine to deglaze, scraping up any browned bits from the bottom of the pot. Simmer for about 2 minutes, until mostly reduced.

Pour in the chicken stock and bring to a gentle boil. Add the Parmesan rind and seared chicken breasts, then reduce the heat to a simmer. Partially cover and cook for about 15 minutes, or until the chicken reaches an internal temperature of 165°F.

Discard the Parmesan rind, then transfer the chicken to a plate and shred with two forks.

Return the chicken to the pot along with the tortellini. Simmer according to package instructions, or until the tortellini is cooked through and floats to the top.

Pour in the heavy cream and stir to combine. Remove the pot from the heat, then stir in the lemon zest and juice.

Ladle into bowls and garnish with chives, celery leaves, lemon slices, and a drizzle of olive oil. Finish with freshly cracked black pepper and/or an extra sprinkle of red pepper flakes, if you like.