Preheat the oven to 350 degrees F.
Place the stuffing cubes in a large bowl and set aside. In a large saute pan over medium-high heat, add 1 tablespoon butter and 1 tablespoon olive oil. Add the jalapeno, onions, bell peppers, and thyme, then sprinkle with a pinch of salt and black pepper. Cook until the onions and bell peppers are tender, and then add the garlic. Cook until the garlic is tender, and then remove to the bowl with the stuffing cubes. Wipe out the pan with a paper towel and place back on the heat. Add the remaining butter and olive oil to the pan. When the butter is melted and bubbly, add the plantains and sprinkle with salt. Saute, while tossing, until the plantains are golden and caramelized on the edges, 6 to 8 minutes. Pour over the stuffing in the bowl. Add the chicken stock and stir or mix with hands.
Pour and press the stuffing into an 8 by 8-inch oven dish, cover with aluminum foil and bake for 30 minutes. Uncover and cook until the top edges are golden, another 20 minutes.