Stir together cream cheese, 3/4 cup shredded Swiss cheese, mayonnaise, 1/4 cup grated Parmesan cheese, minced shallot, pepper, and salt. Fold in collard greens. Spread in a 3- to 4-cup baking dish; top with 1/4 cup each shredded Swiss and grated Parmesan. Bake at 375°F until bubbly, 30 to 35 minutes. Serve with baguette slices.