Grate 2 zucchini and reserve 2 whole for another use. Put the grated zucchini in a clean kitchen towel and squeeze well to remove the excess water.
In a large bowl combine the zucchini, baking mix, onion, eggs and garlic and season with salt and pepper, to taste. Mix well to thoroughly combine.
Heat the canola oil in a skillet over medium heat. Using a 1/4 cup measure drop about 6 to 8 portions of the zucchini mixture into the skillet. Fry on both sides until golden brown and cooked through, about 3 minutes per side. Remove from the skillet and drain on a paper lined sheet pan.
In a small bowl mix together the sour cream and parsley and season with salt and pepper, to taste. Arrange the zucchini cakes on a serving platter and serve with the sour cream.
In a large bowl combine the flour, baking powder and salt. Cut in the shortening with a pastry knife or fork until the mixture is well blended.