How to Make It
Place a rimmed baking sheet in oven. Preheat oven to 450°F (leave pan in oven as it preheats).
Place sweet potatoes in a microwave-safe dish. Cover with plastic wrap; pierce 2 or 3 times to vent. Microwave at HIGH 5 minutes or until just tender. Cool slightly. Cut each potato lengthwise into 8 wedges; return to dish. Drizzle with 1 tablespoon oil; toss. Remove baking sheet from oven; coat with cooking spray. Arrange potato wedges on pan. Bake at 450°F for 18 minutes, stirring after 9 minutes. Sprinkle with 1/4 teaspoon pepper and 1/4 teaspoon salt.
Heat a large cast-iron skillet over medium-high. Shape beef into 4 (1/2-inch-thick) patties; sprinkle with 1/4 teaspoon pepper and 1/4 teaspoon salt. Coat pan with cooking spray. Add patties to pan; cook 3 minutes on each side. Remove from pan.
Add remaining 1 1/2 teaspoons oil to pan; swirl. Add onion, rosemary, and mushrooms; cook 5 minutes. Add 1/4 cup water, scraping pan to loosen browned bits.
Combine stock and flour in a bowl. Add stock mixture, remaining 1/2 teaspoon pepper, and remaining 1/4 teaspoon salt to mushroom mixture; bring to a boil. Add patties; cook 4 minutes.
Cook beans according to package directions. Place in a bowl. Add butter; toss. Divide potatoes, beans, and patties among 4 plates. Top patties evenly with mushroom mixture and parsley.