Snip through the fatty edges of the chops in a few places to prevent curling in the pan. Season with salt and pepper, brush with the mustard, then coat with the panko.
In a large nonstick skillet, heat the oil over medium-high heat. Add the chops and cook, turning once, until browned, about 8 minutes.
Meanwhile, in a medium nonstick skillet, melt the butter over medium heat. Add the apples and cook, stirring occasionally, until crisp-tender, about 3 minutes. Add the squash and 1/4 cup water; season with salt and pepper. Cover and cook until just heated through, about 3 minutes. Serve with the chops.