Peel and devein the shrimp. Roughly chop half the shrimp and leave the remaining half whole. Transfer to a large bowl and refrigerate until needed. Reserve the shrimp shells.

Place the reserved shrimp shells, onion, head of garlic, bay leaves, kosher salt, and black peppercorns in a large pot. Cover with 10 cups of water. Bring to a boil. Reduce the heat to low and simmer, uncovered, for 30 minutes. Scoop out the garlic and transfer to a small bowl. Strain the stock through a fine-mesh sieve and discard the solids. Wipe out the pot and return it to the stove.

Once the garlic is cool enough to handle, carefully pop out the cloves and mash into a paste. Set aside.

Heat 1 tablespoon extra virgin olive oil in the pot over medium heat. Add the diced onion, celery, jalapeño, and red bell pepper. Season lightly with salt, pepper, and crushed red pepper for extra heat, if desired. Sauté for 6 to 8 minutes until the aromatics begin to soften.

Add the reserved garlic paste and the tomato paste to the pot. Stir until the vegetables are evenly coated. Sauté for 1 minute, until the tomato paste deepens in color. Add the diced potatoes and season lightly with salt. Add the reserved shrimp stock to the pot and bring to a boil.

Reduce the heat to low and cover the pot. Simmer for 30 minutes, or until the potatoes are fork-tender.

Add both cans of clams, including the liquid, and the shrimp. Simmer, uncovered, for 5 to 6 minutes or until the shrimp are cooked through. Stir in the lemon juice. Taste and season with additional salt and black pepper as needed. Remove from heat.

Ladle the chowder into bowls and serve with a drizzle of extra virgin olive oil and oyster crackers. Enjoy!