Bring a large pot of well-salted water to a boil. Add spinach and wilt for 30 seconds. Remove with a wire mesh spider or tongs and rinse in a colander with cold water. Squeeze dry and chop roughly. In the same pot, boil the rice for 10 minutes, keeping it slightly underdone. Drain and spread on a baking sheet to cool, then transfer to a large bowl. Heat oven to 375 degrees. Butter a 2-quart soufflé dish (or other baking dish) and dust with about 2 tablespoons grated Parmesan. Melt 2 tablespoons butter in a small skillet over medium heat. Add almonds and cook, stirring, until golden, about 2 minutes. Season lightly with salt and add contents of skillet to rice. Add remaining Parmesan to rice, along with the ricotta, Gruyère, currants, nutmeg, lemon zest, thyme and sage. Season lightly with salt and add pepper to taste. Add chopped spinach and gently toss rice with hands or wooden spoons to distribute ingredients evenly. Transfer mixture to prepared baking dish. (May be prepared up to this point several hours in advance of baking.) Cover and bake for 30 minutes, then uncover and bake 10 minutes more, until top is browned.