Start by laying the chicken tenderloin on the cutting board with the smooth side down.
Using a sharp knife, with the edge parallel to the cutting board, begin cutting down the length of the side of the tenderloin. Carefully slice it in half width-wise almost to the other edge. Keep that edge intact and open the tenderloin along the "fold."
Cover with plastic wrap and gently pound with the smooth side of a mallet or a rolling pin.
Sprinkle each one with garlic salt and pepper on both sides.
Whisk egg in a separate bowl, and place parmesan cheese on another shallow bowl.
Dip chicken in egg then place in the parmesan dish to cover with cheese both sides.
Press lightly to get it to stick as much as you can and shake off excess cheese. Place flat on a dish and refrigerate for 15 minutes.
Preheat oven to 350F.
On medium-high heat melt butter and oil in a non-stick pan.
Place chicken tenders to cook about 4-5 minutes on one side, lift the chicken slightly to peek and check when it turns golden brown.
Flip to the other side and repeat. *
Place chickens on a baking dish, place about 1 tablespoon of the marinara sauce on each then cover with some shredded mozzarella cheese.
Pop in the oven for 10 minutes or until the cheese melts and gets bubbly.
Garnish with basil leaves or red pepper flakes.