Preheat oven to 400F. Cut 4 sheets of foil, about 12"x12".
Slice zucchini and smoked sausage into bite sized rounds or wedges.
In a large mixing bowl, combine shrimp, sausage, zucchini, peppers, and onion.
Separately, whisk together the Cajun marinade ingredients (olive oil, melted butter, minced garlic, and spices).
Add marinade and cilantro to your shrimp/sausage/veggie mixture and toss to coat.
Divide mixture into four portions and place into the center of each sheet of foil. Fold and seal the foil.
Arrange keto foil packets on a sheet pan, and bake for 16-20 minutes, or until zucchini is tender and shrimp is cooked through.