Bring a large pot of salted water to a boil. Cook the tortellini according to package directions until al dente. Drain and set aside.

In a small bowl, mix the paprika, Italian seasoning, salt, and pepper. If you marinated the chicken in buttermilk, drain it first. Pat the chicken pieces dry with paper towels, then toss them in the spice mixture. Sprinkle the flour over the chicken and stir until evenly coated.

In the same pot you used for the tortellini (make sure it's nonstick), heat the reserved olive oil from the sun-dried tomatoes over medium heat for 30 seconds. Add the basil sprig and garlic, stirring for another 30 seconds.

Increase the heat to medium-high and add the chicken. Cook, stirring occasionally, until the chicken is golden and cooked through, about 6 to 8 minutes. If the pan seems dry, add a little more oil from the sun-dried tomatoes. When the chicken is nearly done, remove the basil sprig and stir in the sun-dried tomatoes. Cook until the chicken is fully cooked.

Return the drained tortellini to the pot with the chicken. Reduce the heat to low and gently stir for 1 to 2 minutes until everything is heated through. Remove from heat.

Stir in the basil pesto and 1 to 2 tablespoons of oil from the sun-dried tomatoes, if desired. Taste and adjust seasoning with salt, pepper, and red pepper flakes.

Divide the skillet mixture among plates. Garnish with fresh basil and sprinkle with grated Parmesan cheese. Serve immediately.