1. Preheat oven to 400°F. Prick potatoes all over with fork; bake for about 1 hour or until tender. Halve potatoes, scoop out pulp and mash until smooth.
2. Meanwhile, on parchment paper–lined baking sheet, toss together carrots, 2 tablespoons olive oil, 2 teaspoons salt, and pepper. Roast for 25 to 30 minutes or until tender and browned. Reserve half of the roasted carrots; set aside. In food processor, purée remaining carrots and 1/4 cup water. Transfer to bowl.
3. In saucepan set over medium-low heat, cook carrot pureé, cream, 1/4 cup Parmesan, lemon juice, 1 teaspoon salt and pepper for 5 minutes; set aside.
4. Stir 2 teaspoons salt and egg into potato mixture. Add 1/4 cup carrot mixture, and flour, kneading gently to form dough. Transfer to lightly floured surface; divide dough into 4 pieces. Line baking sheet with parchment paper; sprinkle with flour.
5. Roll each piece of dough into 12-inch long rope. Use knife or bench scraper, cut each rope into 1-inch piece; transfer to prepared baking sheet.
6. Bring large pot of salted water to boil over high heat. Add gnocchi; cook for 3 to 5 minutes or until they rise to the surface.
7. Meanwhile, heat remaining olive oil in large skillet set over medium-high heat; add butter, stirring until melted. Add reserved carrots, sage leaves and remaining salt. Cook for 3 to 5 minutes or until fragrant and sage leaves are crispy. Remove from heat.
8. Toss gnocchi gently with remaining carrot mixture, roasted carrots and crispy sage. Top with remaining Parmesan and lemon zest.

 
Tip: 

• Use store-bought gnocchi to simplify this dish for a weeknight dinner. Prepare gnocchi according to package directions while carrots are roasting.
  Save potato skins – bake them to make loaded potato skins or chips!