Preheat the oven to 400 degrees F.
Making the prosciutto cups: Line 12 mini-muffin cups with the halved prosciutto slices.
Making the spinach: Heat the olive oil in a large saute pan and cook the garlic over medium-high heat until golden, about 30 seconds. Add the spinach and saute, stirring continuously until the spinach just begins to brown, 2 to 3 minutes. Remove from the heat and let cool slightly.
Making the eggs: Add the eggs, mascarpone, lemon zest, pepper and nutmeg to a large measuring cup with a spout. With a hand-held blender, puree for 30 seconds.
Making the quiche: Divide the sauteed spinach among the prosciutto cups. Pour the egg mixture carefully over the spinach. Sprinkle each cup with the chives.
Bake the cups until the eggs are cooked and the prosciutto is crispy, about 10 minutes. Serve warm.