Method

1. Preheat the oven to 400°F / 200°C.
2. Use 2 slices of prosciutto to line each of 8 standard muffin cups (it’s best to use 2 muffin pans each with 12 cups so that each set of prosciutto slices do not overlap the others).
3. Set the muffin pans on large rimmed baking sheets to catch any drips and bake for 18 minutes, or until the prosciutto shrinks, becomes crisp, and forms cups.
4. Meanwhile, bring a large skillet of water to a simmer over medium heat. Stir in the vinegar.
5. Crack one egg into a coffee cup or small bowl and then gently transfer the egg to the simmering water. Repeat with 3 more eggs.
6. Cook the eggs for about 3 minutes, or until the whites are set but the yolks are still runny.
7. Using a slotted spoon, carefully remove the eggs from the simmering water and set them on a paper towel to drain the excess water.
8. Repeat with the remaining 4 eggs.
9. Meanwhile, melt the butter in a large sauté pan over high heat. Add the spinach and sauté for 2 minutes, or just until the spinach wilts.
10. Set the toasted bagel halves cut side up on 4 plates. Spoon the wilted spinach atop the bagels, dividing evenly. Set the prosciutto cups atop the bagels. Spoon the eggs into the prosciutto cups and serve.