Toasting gives dishes a nutty undertone.
In a small saucepan, heat the stock and saffron over medium until hot. Keep warm over low heat.
In a large saucepan with a lid, heat the butter over medium-high. When the butter foams, add the pasta and cook, stirring often, until golden brown, about 1 minute. Add the rice; season with salt and pepper. Cook, stirring constantly, until the rice is coated and begins to turn translucent around the edges, about 1 minute. Add 2 cups saffron stock and bring to a simmer. Reduce the heat to low, cover and cook until the rice is tender, about 15 minutes. Remove from the heat; let stand while you make the chickpea stew.
In a large skillet, heat the oil, two turns of the pan, over medium-high. Add the chorizo and cook, stirring often, until browned, about 5 minutes; using a slotted spoon, transfer to a medium bowl. Add the onion and garlic to the skillet and cook, stirring constantly, until softened, 2 to 3 minutes. Add the chickpeas, greens and piquillos. Stir until the greens wilt, about 3 minutes. Add the remaining saffron stock; reduce the heat to low.
Stir the tomato and chorizo into the skillet; season.
Divide the pilaf among shallow bowls; top with the chickpea stew.