Place chicken in a mixing bowl along with the red curry paste and 2 tablespoons avocado oil. Stir well and allow meat to marinate at least 15 minutes (up to 2 hours in the refrigerator).
While chicken is marinating, peel and chop the butternut squash into 1-inch cubes.
Heat 1 tablespoon avocado oil in a large pot or Dutch oven over medium heat. Add the chicken and brown 2 to 3 minutes (don’t cook meat all the way through).
Add the remaining ingredients except the kaffir lime leaves and almond butter (butternut squash through sea salt) to the pot and stir well. Cover and bring to a full boil. Reduce heat to low and cook, covered for 1 hour. Remove the cover and cook at a gentle boil for 30 minutes, stirring occasionally, until sauce has thickened. Stir in the kaffir lime leaves. Stir in the almond butter for an even thicker, more luscious sauce.
Remove cinnamon sticks and star anise.
Serve massaman curry with basmati rice (or spaghetti squash or cauliflower rice).
*Or peanut butter