Preheat oven to 400°F. Set a 12-cup muffin pan nearby. Heat oil in large nonstick skillet over medium-high heat. Add mushrooms and cook until golden, 4 minutes. Stir in asparagus (stalks and tips) and shallots. Cook just until vegetables are softened, about 2 minutes. Stir in Sofrito and place in bowl to cool.
Prick pastry rounds with fork. Place in muffin cups, pressing into bottoms and up sides.
Bake pastry until just golden, about 10 minutes. Place on rack to cool for 10 minutes. Spoon queso blanco into bottoms of pastry cups. Toss Manchego with mushroom and asparagus mixture and spoon into cups.
Return filled pastry cups to oven and bake until golden brown and heated through, about 12 minutes. Cool in pan on rack for 10 minutes. Loosen sides of cups with sharp knife and remove from pan. Top with Serrano ham, if using.
• Leaving out the ham will make these a vegetarian first course.
• You can prepare these up to 2 hours in advance (without Serrano ham). Reheat in a 325°F oven for 8-10 minutes or just until warmed in the center.