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

If marinating, place chicken pieces in a bowl with buttermilk, cover, and refrigerate for 4-6 hours. Drain before using. If not marinating, pat chicken dry with paper towels.

In a small bowl, mix paprika, Italian seasoning, salt, and pepper. Toss the chicken pieces with the seasoning mixture, then sprinkle with flour and toss to coat evenly.

In the same pot used for tortellini (nonstick preferred), heat 3 tablespoons of oil from the sun-dried tomatoes (or olive oil) over medium heat for 30 seconds. Add the basil sprig and garlic, stirring for 30 seconds until fragrant.

Add the seasoned chicken to the pot. Cook, stirring occasionally, until golden and cooked through (about 6-8 minutes). If needed, add a little more oil. When chicken is nearly done, remove the basil sprig and stir in the sun-dried tomatoes. Cook 1-2 minutes more.

Return the drained tortellini to the pot with the chicken. Reduce heat to low and gently stir for 1-2 minutes to warm through.

Remove from heat. Stir in the basil pesto and 1-2 tablespoons of sun-dried tomato oil (or olive oil) until everything is well coated. Taste and adjust seasoning with salt, pepper, and red pepper flakes if desired.

Divide among plates. Garnish with fresh basil leaves and a sprinkle of grated Parmesan cheese. Serve immediately.