Heat the oil over medium-high heat in a medium skillet. Add the pancetta and cook until lightly browned, about 5 minutes. Remove the pancetta using a slotted spoon, drain on paper towels and allow to cool slightly. Add the shallots and cook over medium-high heat until soft, about 3 minutes. Add the spinach and cook until just wilted, 1-2 minutes.
In a medium bowl, mix together the cooked pancetta, bread, eggs, gruyere, milk and shallot and spinach mixture until all the ingredients are moistened.
Spoon the mixture into the ramekins, filling each ¾ full. Place the ramekins on a small baking sheet and bake until golden brown, about 25 - 35 minutes.
Allow time to cool before you turn them over and pop out the muffins. Serve warm or at room temperature.
Recipe by FEASTS AND FOTOS at https://www.feastsandfotos.com/2012/10/12/egg-muffins/