Evenly spread the frozen fries on a rimmed baking sheet. Bake until lightly browned, 15 to 20 minutes.
While the fries are baking, brown the chorizo. Cook the chorizo in a large skillet over medium-high heat, using a wooden spoon to break it up, until browned, 7 to 10 minutes. Transfer to a paper towel lined plate to drain.
Make the crema. Whisk together the sour cream, grated garlic and a few teaspoons of water to create a thick sauce.
Top the fries with the chorizo, manchego, mozzarella and pimentos. Bake until the fries are golden brown and the cheese is melted and bubbly, 10 to 15 minutes. Drizzle with the crema and top with fresh parsley.