1. Melt the butter in a small saucepan over medium heat. Add the apricot preserves, balsamic vinegar, and red pepper flakes. Season with salt. Bring to a boil, reduce heat to medium low and let simmer until sauce is thickened (about 3 - 5 minutes). Remove from heat and let cool.
2. Pound chicken breasts to an even thickness. Drizzle with a little olive oil and season with salt and pepper.
3. Grill breasts over medium heat for 7 - 8 minutes per side or until almost done. Brush on glaze on each side and cook 30 seconds more per side to caramelize the glaze. Remove from grill.
4. Brush on more glaze before serving.