To make homemade shrimp stock: this step is optional but absolutely worth it (especially if you purchased shrimp with the shells and tails left on).
Start by thawing the shrimp (if frozen). Remove shells and tails (or leave tails on – up to you). Transfer the shrimp to a large bowl and set aside in the refrigerator until ready to use. Meanwhile, add the shells to a large pot. Add the roughly chopped onion, smashed garlic, and bay leaves. Fill with at least 4-5 cups of water.
Bring to a boil over high heat before reducing to low heat. Cover and simmer for 45-60 minutes. Strain the broth through a fine-mesh strainer into a separate pot or container. Measure out the desired amount (I used 4 cups).
Prepare the herb blend by combining the chopped parsley, fresh lemon juice, olive oil, and garlic in a small bowl. Mix to combine and set aside.
Combine your stock. Once your homemade shrimp stock has been strained and measured, transfer the desired amount (in my case, I used 4 cups) to a medium stockpot with 2 cups chicken broth and 1 cup white wine (you need 7 cups of liquid total). Bring to a gentle simmer over medium heat. Add the saffron, mix well to combine, and reduce heat to low. Cover and gently simmer until needed.
Peel and devein the shrimp (if you haven’t done so already), leaving the tails on, or removing them (up to you). Set aside, you’ll need them in a sec.
Heat 1 tablespoon of olive oil in a large paella pan over medium-high heat. Add the sliced sausage and cook for 2-3 minutes, stirring as needed (see notes). Remove from pan to a clean plate. Set aside.
Add the shrimp to the pan (add additional olive oil, if needed). Cook shrimp for 1-2 minutes on each side, or until nearly cooked. Remove from the pan to a clean plate. Set aside.
Reduce heat to medium. Add one more tablespoon of olive oil and add the onions and bell pepper. Mix thoroughly to combine. Cook, stirring often, for 10-15 minutes. Add the salt and garlic, cook for an additional minute before adding the diced tomatoes, sweet paprika, and thawed (and drained) calamari. Cook, stirring often, for an additional 3-5 minutes.
Add the dry rice to the pan and mix thoroughly with the aromatics. Allow the rice to toast for 1-2 minutes, stirring occasionally.
Add the herb mixture, thawed peas, sausage, and slowly add the broth. Mix thoroughly to combine and stir the rice often. Bring to a boil, then reduce heat to medium-low heat. Stir for approximately 5 minutes then stop stirring for the remainder of the cooking time.
Cook, uncovered for 15 minutes.
Nestle the clams, mussels, and shrimp into the rice mixture. Cook for 5-10 minutes, or until shells open (discard any unopened shells). Rotate the pan every few minutes to ensure even cooking.
Remove from heat, drizzle with fresh lemon juice, and cover with a towel. Allow paella to rest for 5-10 minutes before serving. Garnish with fresh parsley and lemon wedges, if desired.