Place potatoes on a baking sheet. Drizzle with oil and sprinkle with 1/2 teaspoon salt. Bake at 425° for 20-25 minutes or until tender., Meanwhile, in a Dutch oven, saute onions in butter until tender. Reduce heat to medium-low; cook for 30 minutes or until deep golden brown, stirring occasionally. Add the mushrooms, sunflower kernels, rosemary, pepper and remaining salt. Cook 8-10 minutes longer or until mushrooms are tender. Stir in the broth, beer, brown sugar and potatoes; heat through., Place bread slices on a baking sheet; top with cheeses. Broil 3-4 inches from the heat for 3-5 minutes or until cheese is melted. Ladle soup into bowls; top each with a cheese toast. Serve immediately.