1Heat oven to 400°F. Rinse all fish and pat dry with paper towel. Mince 2 cloves garlic, and halve remaining clove. Peel onion and cut into small dice. Rinse parsley and pick leaves, discarding stems. Trim and discard dark top of leek. Halve lights and white greens and thinly slice. Place in a bowl of cold water and allow dirt to sink to bottom.
2Heat olive oil and 1 packet butter in a large high-sided pan over medium-high heat. Add minced garlic and red chile flakes, if desired, and sauté until fragrant, about 1 minute. Add onion and leek and sauté until softening, about 5 minutes. Meanwhile, add tomatoes and their juices to a medium bowl and crush tomatoes by hand.
3Add Pernod/white wine to pan with aromatics, scraping up any browned bits on bottom of pan. Cook until reduced by half, about 1 minute. Add saffron, chicken broth, and tomatoes and their juices. Stir to combine. Increase heat to high and bring to a boil, then cover pan, reduce heat to medium, and simmer until flavors meld and reduced slightly, about 5 minutes.
4Season pollock on rounded sides with salt and black pepper. Uncover broth and nestle in pollock. Cover and simmer until pollock is almost cooked through, about 5 minutes. Uncover, add calamari and crab, and stir to combine. Simmer, uncovered, until crab is bright red and calamari is opaque, about 3 minutes.
5While fish cooks, halve bread lengthwise and spread remaining butter evenly over cut sides. Heat a medium pan over medium heat, then add bread cut-side down. Toast until light golden, about 3 minutes, then flip and cook about 2 minutes more. Immediately rub cut sides of bread with cut sides of halved garlic.
6Taste bouillabaisse and add salt and black pepper as needed. Gently break up cooked pollock into large chunks using a fork. Divide broth and fish evenly between 2 bowls. Garnish with parsley and serve garlic toasts alongside.