How-to Flatten Chicken Breasts (Technique 2)
Hold sharp knife parallel to cutting board and along one long side of breast; cut almost in half, leaving breast attached at one side.
Open breast so it lies flat; cover with plastic wrap. Using flat side of a meat mallet, lightly pound to 1/4-in. thickness.
Remove plastic wrap and stuff according to recipe.
Roll up jelly roll-style, tucking in sides. Secure with toothpicks.