Core, pit, and peel peaches; put one peach in a blender and set the other two aside for use later. Add jalapeño jelly, Dijon mustard, olive oil and vinegar to blender and blend at high speed until combined. Set aside.
Prepare salad dried red pepper flakes in a large bowl; toss together spring mix and sliced green onions. Top with sugared pecans, cheese, and the remaining two peaches which have been thinly sliced. Dress with sweet-heat peach vinaigrette when ready to serve.