Slice bacon into 1/2 inch pieces, slice the shallots thin. In a deep pot add bacon a sliced shallots of low heat and cook until fat renders out of the bacon. Cook until the bacon colors and deglaze with the apple cider vinegar. Immediately begin to add the collard greens handfuls at a time, they will wilt in the pot. Cook the greens covered until they soften.
While they cook combine the milk and cream cheese in a pot and warm the mixture until the cream cheese breaks up into the milk. Once the greens are fully cooked, add the milk and cream cheese mixture. Remove from the heat and add the parmesan. Season with salt and pepper and stir to combine.
In a small bowl combine the panko bread crumbs with the olive oil season with salt and pepper. Take the collard green mixture and lay it in a large cast iron skillet and top with the panko breadcrumbs. Bake for about ten minutes, or until golden brown on top, bubbling and thickened. Allow to cool slightly.