Set the oven to 375°F. Place sliced onions and garlic cloves in the bottom of a small casserole dish and lay the thyme sprigs over. Pour wine over onions and garlic and sprinkle the vegetables with salt and white pepper.
Heat olive oil in a small skillet until the surface just begins to shimmer. Add chicken thighs to the skillet and sear until browned on each side.
Once browned (the chicken will not be cooked all the way through), remove chicken from skillet and place, on top of vegetables in casserole dish. Pour any pan juices that have accumulated in the skillet over the chicken and vegetables and reserve the skillet for later use. Cover the dish with foil and place in oven for 20-25 minutes, or until the chicken reaches an internal temperature of 165 degrees Fahrenheit and the vegetables are very soft.
While the chicken is in the oven, make the crispy sausage bread crumbs: place a heat-proof bowl and a plate next to the stove. Wipe out the skillet used to sear the chicken and heat 2 teaspoons olive oil over a medium flame. Add sausage and use a spatula or a wooden spoon to break up into small pieces. Cook sausage, stirring frequently, until completely cooked through and beginning to crisp up a bit.
Remove skillet from stove and carefully pour out all but a tablespoon or so of accumulated oil into the heat-safe bowl, leaving the sausage in the skillet. Return skillet to stove, add bread crumbs and a healthy pinch of kosher salt.
Saute bread crumbs and sausage, stirring constantly, until all remaining oil in the skillet has been absorbed by the bread crumbs and the mixture is browned and crispy. Carefully scrape out sausage bread crumbs onto the plate and taste for seasoning, adding salt if necessary.
When the chicken is cooked through, remove from oven and carefully remove chicken from the casserole dish, setting aside to cool slightly. Scrape the softened onion and garlic along with any liquid in the bottom of the dish into the basin of a high-powered blender or a food processor. (A blender will result in a very smooth dip, but if you prefer a chunkier texture, a food processor will work nicely)
Add the drained and rinsed cannellini beans, lemon juice, and salt to the blender along with vegetables. Process until very smooth, adding a drizzle of olive oil if necessary to keep things moving. Taste and adjust seasoning as necessary-- you may find that you need more salt or more lemon juice to really punch up the flavors.
When the chicken is cool enough to handle, shred chicken meat into bite-sized pieces.
Toss the baguette slices with olive oil and salt. Arrange on a sheet tray and bake for 10-12 minutes, rotating the tray once in the middle of baking, until the slices are browned and crisp.
Spoon bean mixture into a large bowl or plate, leaving a slight divot in the center of the dip. Pile shredded chicken into divot. Scatter a healthy handful of crispy sausage bread crumbs over chicken (you may find yourself with leftover breadcrumbs, use them to garnish your next bowl of pasta!) and drizzle a little olive oil over the whole plate. Garnish with fresh thyme and parsley leaves and serve with toasted baguette rounds on the side.