Blot the chicken thighs dry with paper towels. This helps the surface brown instead of steam once it hits the hot skillet.
Mix 1 teaspoon kosher salt, ½ teaspoon black pepper, and ½ teaspoon chili powder in a small bowl. You want the spices evenly combined so the chicken seasons consistently.
Rub the seasoning mixture over the chicken thighs on all sides. The surface should look evenly coated, with no heavy clumps of spice.
Heat 2 tablespoons extra virgin olive oil in a large nonstick skillet over medium heat, then add the chicken in a single layer and cook for 5 minutes. When the first side is ready, it should be golden and release from the pan easily.
Turn the chicken, lower the heat to medium-low, and cook 5 minutes more until the thickest part reaches 165°F. The chicken should feel firm but still springy, not tight or dry.
Move the chicken to a plate and tent it loosely to keep warm. Resting keeps the juices in the meat while you finish the skillet sauce.
Return the skillet to medium heat and add the sliced jalapeno pepper, cooking for 3 minutes. You’ll smell the pepper bloom almost right away, and the slices should soften slightly.
Add the sliced peaches and cook for 3 minutes more. The peaches should soften at the edges while still holding their shape.
Pour in the peach glaze and stir to coat the jalapeños and peaches. After a short simmer, the glaze should look shiny and thick enough to coat the back of a spoon.
Return the chicken to the skillet, spoon the glaze over the top, and warm for 1 to 2 minutes. The chicken should be heated through and lightly lacquered with sauce.
Serve warm. Each piece should have juicy chicken, soft peaches, and a glossy sweet spicy finish.