Make the glaze

1. In a medium bowl, whisk together the peach preserves, olive oil, soy sauce, apple cider vinegar, Dijon, minced garlic, salt, black pepper, and red pepper flakes until smooth. Set aside.

Prepare and season the chicken
2. Pat the chicken thighs dry with paper towels.
3. In a small bowl, mix the kosher salt, black pepper, and chili powder. Rub this seasoning evenly over both sides of each thigh.

Sear the chicken
4. Heat 2 tablespoons of olive oil in a large nonstick skillet over medium heat. When the oil shimmers, add the chicken (work in batches if needed so the pan doesn’t crowd). Cook for about 5 minutes on the first side.
5. Flip the thighs, turn the heat to medium–low, and cook another 5 minutes, or until an instant-read thermometer registers 165°F. Transfer the cooked chicken to a plate and tent loosely to keep warm.

Cook the aromatics and peaches
6. Raise the skillet heat back to medium. Add the sliced jalapeño and sauté for about 3 minutes until fragrant.
7. Add the peach slices to the pan and cook an additional 3 minutes, stirring occasionally, until the peaches start to soften.

Finish with the glaze and rewarm the chicken
8. Pour the prepared peach glaze into the skillet, stirring so the peaches and jalapeños become well coated. Let the sauce bubble for a minute to warm through.
9. Return the chicken thighs to the pan, spoon glaze over each piece, and cook 1–2 minutes more so everything is hot and glossy.

Serve
10. Transfer to plates and serve warm, spooning extra glaze over the chicken.