MELT butter, in medium skillet. Pour 2 tablespoons of melted butter into small bowl; add breadcrumbs, tossing to combine. Set aside.
ADD oil to butter remaining in skillet and increase heat to high.
ADD mussels, shallot and garlic and sauté until mussels begin to open.
ADD half of parsley and tarragon and sauté for an additional 1 to 2 minutes.
ADD cream, wine and 2 tablespoons of Parmesan cheese; cook until liquid is reduced by half.
TRANSFER mussels to oven-proof baking dish; sprinkle top with reserved breadcrumbs and cheddar. Bake for 3 to 4 minutes or until browned. Remove from oven and sprinkle with remaining Parmesan and herbs.