Cut the chicken into bite size pieces, feel free to use boneless skinless breasts or boneless skinless thighs or a combination of both. In a medium bowl or shallow pie plate, toss the cubed chicken with the paprika, flour, salt and pepper. Toss to coat.
Heat the olive oil in a large skillet over medium heat until hot. Add the chicken in a single layer and cook until golden brown on each side, tossing occasionally, about 5 minutes. The chicken will finish cooking fully a bit later so it doesn’t need to be cooked all the way through. Put the chicken on a plate and set aside.
Add another teaspoon of oil to the pan, if needed, and stir in the onions and mushrooms. Saute the mixture, stirring occasionally and scraping up the browned bits from the chicken, until the onion is translucent and the onions and mushrooms are browned, about 5 minutes. Add the garlic and cook for another minute, until fragrant.
Pour in about 1/4 cup of the chicken broth and deglaze the pan by scraping up any bits from the bottom. Stir in the tomato paste, whisking to combine. Add the rest of the chicken broth and the bay leaf, stirring well.
Add the chicken back into the skillet and simmer the mixture over medium-low to medium heat, until the chicken is cooked through and the sauce thickens slightly, about 5-6 minutes. Stir in the yogurt (or sour cream) and cook for about 2-3 minutes longer.
If you would like the sauce to be a bit thicker, make a cornstarch slurry by mixing 1 tablespoon cornstarch with 2 tablespoons cold water. Add the cornstarch slurry to the simmering mixture in the skillet, whisking quickly to combine.
Let the mixture simmer for 2-3 minutes until thickened.
Serve over hot pasta and garnish with fresh parsley, if desired.