Make the glaze: Whisk all glaze ingredients in a bowl. Set aside.
Season chicken: Pat thighs dry, then rub with salt, pepper, and chili powder.
Cook chicken: Heat oil in skillet over medium. Sear chicken 5 mins per side until 165°F. Remove and tent.
Sauté veggies: In same skillet, cook jalapeños 3 mins. Add peaches; cook 3 more mins.
Glaze it up: Pour in peach glaze, stir to coat. Return chicken, spooning sauce over top. Simmer 1-2 mins.
Serve: Garnish with fresh jalapeño slices.