Bring a large pot of salted water to a boil and cook tortellini according to package directions until al dente; drain and set aside.
Season chicken cubes with salt, black pepper, and dried oregano.
In a large skillet over medium-high heat, melt 1 tablespoon of butter. Add chicken and sear until golden brown and internal temperature reaches 165°F (74°C), approximately 6 to 8 minutes. Remove chicken from skillet and set aside.
Lower heat to medium and add the remaining 2 tablespoons of butter to the same skillet. Once melted, add minced garlic and red pepper flakes; sauté for 1 minute until fragrant.
Deglaze the skillet with chicken broth, scraping up browned bits from the bottom. Pour in heavy cream and bring to a gentle simmer for 3 to 4 minutes until slightly thickened.
Gradually whisk in the Parmesan cheese until fully incorporated and the sauce is smooth.
Add fresh baby spinach to the sauce and stir until wilted, approximately 1 minute.
Fold the cooked chicken and tortellini back into the skillet. Toss to ensure even coating in the sauce.
Garnish with chopped Italian parsley and serve immediately.