In small resealable food-storage bag, place raspberry preserves; seal top, and cut 1/8-inch tip from corner. Using small knife, insert and twist in side of muffin to make small hole. Insert tip of bag into hole; gently squeeze bag until muffin expands slightly, but does not burst. Fill muffin with heaping 1/2 teaspoon preserves with a little coming out on side. Repeat steps to make a hole and fill remaining muffins, working one at a time.