In a large dutch oven, heat the EVOO over medium-low heat. Add the onion and cook, stirring occasionally, until browned, about 15 minutes. Meanwhile, mash 1 cup beans in a bowl with the back of a fork. Stir into the onion; set aside.
In a large pot of boiling, salted water, cook the collards for 10 minutes. Drain well and set aside.
Meanwhile, add the bacon to the dutch oven and cook until the fat is rendered and the bacon is browned but not crisp, about 7 minutes; transfer the meat to a plate. Pour out all but 2 tbsp. of the bacon fat from the pot and reserve. Increase the heat to medium-high. Season the pork with salt and pepper. Working in batches, add the pork to the pan in a single layer and brown on all sides, about 5 minutes per batch. Transfer to a plate.
Add the chorizo to the dutch oven and cook, stirring, for 1 minute. Stir in half of the garlic for 15 seconds. Stir in the pork, bacon, onion mixture, remaining beans and the bay leaves. Pour in the broth and simmer until the pork is just cooked through and the stew has thickened, about 15 minutes. Discard the bay leaves. Season with salt and pepper.
Just before the stew is done, heat the reserved bacon fat in the large pot over medium-high heat. Add the cooked collards and remaining garlic; season with salt and pepper. Heat through. Serve with the stew and orange slices.