Saute the onion in the butter in a medium skillet until translucent and tender

Mix the chicken, cream cheese and pimentos in a medium bowl, add the cooked onion and gently mix well

Open and unroll the crescent rolls, separate each triangle and using a rolling pin, roll them out just a little on a pastry mat

Spoon a generous two tablespoons of the chicken mixture onto the widest area of the crescent roll, fold up the sides and gently roll, ending with the smallest end of the triangle, covering the chicken filling completely with the dough. Repeat until all chicken rolls are completed

Place on nonstick cookie sheet and bake at 350 degrees for 10-12 minutes until golden brown.