Light a grill or preheat a grill pan. Brush the bread with olive oil and grill over high heat, turning once, until lightly charred, about 2 minutes. Transfer to a work surface.
Working over a medium bowl, grate the tomatillo halves on the large holes of a box grater until only the skins remain; discard the skins. Stir in the 2 tablespoons of olive oil and the crushed red pepper. Season generously with salt and black pepper.
Spoon the tomatillo mixture evenly on the toasts and top with the prosciutto. Top generously with shaved Manchego and serve right away.
