Preparation Preheat oven to 425°F. Toss squash, 2 tablespoons oil, and sugar in a large bowl. Season with salt and pepper. Arrange in a single layer on a rimmed baking sheet. Roast, tossing occasionally, until squash is golden and tender, 25-30 minutes. Let cool on sheet. Heat 1 1/2 tablespoons oil in a small skillet over medium-high heat. Add sage; cook until edges begin to curl and turn dark green, 1-2 minutes. Using a slotted spoon, carefully transfer to paper towels to drain. Mix ricotta and lemon zest in a small bowl. Season with salt and pepper. DO AHEAD: Butternut squash, sage leaves, and ricotta can be made 1 day ahead. Cover and chill squash. Store sage airtight at room temperature. Cover and chill ricotta mixture. Bring squash to room temperature before serving. Spread 1 tablespoon of ricotta mixture on each baguette slice. Top each with a few squash cubes. Drizzle crostini with lemon juice and olive oil. Sprinkle with salt and pepper. Top crostini with 2 fried sage leaves each.