1 1/2 tablespoons olive oil
Salt and freshly ground black pepper
Heat a large heavy sauté pan over medium-high heat. Add the oil, then add the onions and sauté until translucent, about 3 minutes. Add the garlic and cook until fragrant, about 30 seconds. Add the spinach, 1 handful at a time, and sauté just until the spinach wilts, about 3 minutes. Transfer the spinach to a sieve and press to exude the excess liquid.
Bring the cream to a boil in the same sauté pan over high heat. Add the spinach and toss to coat, cooking until the spinach is heated through. Remove the pan from the heat.
Coarsely crumble the blue cheese over the spinach and toss to coat. Season to taste with salt and pepper and serve.