This is a borrowed recipe with some slight variations.
Preheat the oven to 425 degrees. Oil a 2-quart baking dish or gratin and rub with a cut side of one of the garlic cloves before you chop the garlic.
Steam the spinach above an inch of boiling water for 2 to 3 minutes, until it is wilted. Rinse briefly with cold water, squeeze gently (you don’t have to squeeze dry) and chop.
In a large bowl, toss together the spinach, 2 tablespoons of the olive oil, garlic, salt and pepper, flour, milk and parsley. Spoon into the gratin dish in an even layer. Sprinkle the bread crumbs over the top and drizzle on the remaining tablespoon of olive oil.
Optionally: Sprinkle cheese, sliced onions on top of the gratin before baking.
Place in the oven and bake for 20 to 30 minutes, until the top is browned and the mixture is sizzling. Serve as a starter or a side.