How to Make It
Preheat the oven to 400°.
Place the potatoes in a large pot of salted water and bring to a boil. Cook, uncovered, until the potatoes are fork tender, about 15 minutes. During the last minute of cooking, add the spinach.
Drain, shaking out any excess water and return to the pot. Add the oil and mash the potatoes until smooth. Stir in the stock and season with salt and pepper to taste.
Transfer the potatoes to a 3-quart ceramic baking dish and sprinkle the breadcrumbs over the top. Bake for 15 minutes, until the top is lightly browned and serve warm.