Heat olive oil in a large deep skillet or Dutch oven over medium-high heat.
Season chicken thighs with salt and freshly ground black pepper on both sides.
Add chicken thighs to the skillet skin side down and sear until golden brown, about 5-6 minutes per side. Remove chicken and set aside.
In the same skillet, add sliced onion and cook for 3-4 minutes until softened.
Add minced garlic and cook for 1 minute until fragrant.
Add sliced red and green bell peppers and cook for 4-5 minutes until slightly softened.
Pour in the white wine and cook for 2 minutes, scraping the bottom of the pan to release any browned bits.
Add diced tomatoes with their juices, chicken broth, dried oregano, dried basil, and crushed red pepper flakes. Stir to combine.
Return the chicken thighs to the skillet, nestling them into the sauce.
Reduce heat to medium-low, cover, and simmer for 30 minutes until the chicken is cooked through and tender.
Remove the lid and cook uncovered for an additional 5 minutes to thicken the sauce slightly.
Taste and adjust seasoning with salt and freshly ground black pepper as needed.
Sprinkle chopped fresh parsley over the top before serving.