1. Heat 1 teaspoon oil in a large skillet over medium-high heat. Add lamb; cook 5 minutes, stirring to crumble. Remove lamb from pan with a slotted spoon; sprinkle with 1/4 teaspoon salt. Discard drippings from pan. Reduce heat to medium-low. Add 2 teaspoons oil, onion, and carrot; cook 5 minutes or until tender, stirring occasionally. Add rosemary and garlic; cook 1 minute, stirring constantly.
2. Return lamb to pan; add wine. Increase heat to medium-high; cook for 3 minutes or until liquid almost evaporates. Add remaining 1/2 teaspoon salt and pepper. Stir in tomatoes and broth; bring to a simmer. Partially cover and simmer 10 minutes, stirring occasionally.
3. While sauce simmers, cook pasta according to package directions. Drain; return pasta to pan. Stir in 1 cup sauce and remaining 1 teaspoon oil. Spoon 1 cup pasta mixture onto each of 4 plates; top each serving with 3/4 cup remaining sauce, 2 tablespoons ricotta, and 1 tablespoon mint.