Stir chicken stock and eggs together in a bowl; whisk baking mix into egg mixture until wet. Stir squash, onion, Parmesan cheese, and garlic into baking mix-egg mixture until batter is evenly mixed. Set aside for 5 minutes.
Heat oil in a large skillet to 350 degrees F (175 degrees C).
Spoon batter, 1/4 cup per pancake, into the hot oil; cook until pancakes are golden brown, 2 to 3 minutes per side. Transfer pancakes to a brown paper bag-lined surface to drain.