Warm olive oil in a large, cast-iron pot over medium heat. Add the chopped fennel and onion along with a big pinch of salt, and cook, stirring occasionally until soft (about 5 minutes). Stir in garlic, fennel seeds and saffron, and cook until fragrant (about 1 minute). Add diced tomatoes (with all of the juices), chickpeas, 1/2 cup water, a couple pinches of salt and several turns of black pepper. Let the sauce come to a boil, reduce heat to low, and simmer partially covered for 15 minutes, stirring occasionally. Season to taste with additional salt and pepper.
While the sauce is cooking, bring a large pot of salted water to a boil. Cook ditalini to al dente, using the package instructions as a timing guide. Drain pasta.
If serving the entire amount of pasta and sauce, toss both together in a big bowl and divide between 4 to 6 bowls. If serving just a few portions, spoon pasta into individual bowls, and top with a big spoonful of sauce. Finish each bowl with a sprinkling of black pepper and chopped fennel fronds.
*Option to brine the dried chickpeas overnight and then cook quickly in a pressure cooker. You'll need 1/2 cup dried chickpeas for this recipe.