Prepare the Broth

Place chicken pieces and carcass, dark green parts of leek and scallions, and salt, plus more to taste, in a large pot; add water until just covered. Cover and bring to a simmer over high; reduce heat to medium-low, and cook, uncovered, stirring occasionally and skimming any excess foam from top, until the chicken is fully cooked through, about 1 hour.

Transfer chicken breast, thighs, and drumsticks to a cutting board, and let rest until cool enough to handle, about 10 minutes; discard wings or reserve for another use. Drain Broth through a fine mesh strainer into a large heatproof bowl or pot. Let cool to room temperature, about 30 minutes. Transfer Broth to airtight containers, reserving 3 1/2 cups Broth for Stew and Dough. Shred chicken meat, and set aside; discard skin and bones.

Prepare the Stew

Bring a medium pot of water to a boil over high. Add pork loin, and cook until an instant-read thermometer inserted into thickest portion of pork reads 145°F, about 10 minutes; drain, discarding liquid. Set cooked pork loin aside.

Place pork belly (if using) and oil in a large pot or Dutch oven; cook over medium-high, stirring occasionally, until browned and crispy, about 6 minutes. (Do not remove from pot.)

While pork belly cooks, chop reserved light green parts of leek and scallions. Reduce heat in pot to medium; add white onion and chopped light green parts of leek and scallions; cook, stirring often, until translucent, about 8 minutes.

Add roasted red bell peppers, Moscatel wine, papelón, garlic, ají peppers (if using), and 1 cup of the reserved chicken broth to pot; bring to a simmer over medium heat, about 2 minutes. Add salt, smoked paprika, and black pepper; simmer until flavors meld, about 10 minutes. Add beef stew meat and reserved cooked pork loin; partially cover, and cook over low, stirring occasionally, until meat is tender, about 1 hour. Add reserved shredded chicken; partially cover, and simmer over low, stirring occasionally, until meat shreds easily using a fork, about 30 minutes. Remove from heat; shred beef stew meat and pork loin. Stir in red onion, red bell pepper, olives, raisins, and capers. Transfer to a large bowl, and set aside.

While mixture in pot simmers, prepare the Dough (Masa): Heat oil and annatto seeds in a small saucepan over low; cook stirring occasionally, until fragrant and turns an intense orange-gold color, about 5 minutes. Set annatto seed oil aside, and let cool to room temperature, about 30 minutes.

In a large bowl, stir together precooked cornmeal and 1 cup reserved annatto seed oil. Stir in  remaining 2 1/2 cups reserved chicken broth, 1/2 cup at a time, stirring until fully combined with each addition. Stir in salt, and set aside until ready to use.

Using kitchen shears, cut each banana leaf into 3 sizes: 1 large (14- x 10-inch) rectangle (main leaf that is used for Dough and Stew), 1 medium (10- x 10-inch) square (second wrapper to secure main leaf), and 1 thin (10-inch) strip (to wrap around as a band to prevent other leaves from unfolding before tying with twine).

Remove any center stems from banana leaves without cutting into leaves. (You can pass leaves over an open flame until they are no longer shiny, or microwave in 10-second intervals to make leaves more pliable.)

Working with 1 banana leaf at a time, lay large rectangle leaf flat on a work surface. Brush with enough remaining annatto seed oil to make a thin, even coating on top side. Place 1/2 cup Dough in center of oiled banana leaf rectangle. Using oiled hands, press into a thin, 7-inch round, about 1/8-inch thick. Spoon a scant 2/3 cup Stew over center of Dough.

Fold bottom half of banana leaf over Stew; then fold top half of banana leaf over Stew (so Stew is completely encased by Dough and banana leaf). Pinch open sides closed, and fold under to create a rectangular package. Use medium-size leaf to create a second wrapper, folding in same direction. Use small-size strip to wrap around leaves. Repeat with remaining banana leaves, Dough, and Stew.

Secure banana leaves on all sides using kitchen twine (being careful not to tie too tightly or leaves will crack open).

Place hallacas in a large pot, and add water to cover. Cover pot, and bring to a boil over high. Reduce heat to medium-low; simmer, covered, until plump and firm, about 1 hour.

Transfer hallacas to a plate, and let rest 5 minutes to firm up. Unwrap and serve with or without main banana leaf.