Preheat oven to 400 degrees F. Cut off top 1/2 inch of garlic bulb to expose ends of individual cloves. Leaving bulb whole, remove any loose, papery outer layers. Place bulb, cut end up, on a double thickness of foil. Drizzle bulb with 1 tsp. oil. Bring foil up around bulb and fold edges together to loosely enclose. Roast garlic 50 to 60 minutes or until tender; cool.

Meanwhile, thaw fish and shrimp, if frozen. Peel and devein shrimp, leaving tails intact if desired. Rinse fish and shrimp; pat dry. Cut fish into 2-inch pieces. Scrub mussels under cold running water. Using your fingers, pull out beards that are visible between the shells.

In a 6-qt. Dutch oven heat 2 Tbsp. of the oil over medium. Add parsley and minced garlic; cook and stir 30 seconds. Add tomato paste; cook and stir 1 minute more. Add wine. Cook over high 5 minutes or until wine is evaporated, stirring frequently. Add tomatoes, crushed red pepper and black pepper. Cook 5 minutes or until tomatoes are softened, stirring occasionally. Stir in the water. Simmer, covered, 10 minutes.

Layer fish, shrimp, and mussels on tomato mixture. Cook, covered, without stirring 5 to 7 minutes or until fish flakes easily, shrimp are opaque and mussel shells open. Discard any mussels that do not open.

To prepare the garlic crostini, brush both sides of bread with remaining 1 Tbsp. oil. Place bread on a baking sheet. Bake 3 to 5 minutes or until toasted. Squeeze garlic bulb from bottom of paper husk so cloves pop out. Spread bread with roasted garlic.

If desired, sprinkle servings with additional parsley. Serve with garlic crostini.