Preheat the oven to 150°C. Place the panettone cubes on a parchment lined baking sheet. Bake until dark golden brown and crispy on the outside, about 45 to 50 minutes. Remove from the oven and set aside. The croutons will continue to crisp up as they cool.
Increase the oven temperature to 220°C. Place the fruit in a large mixing bowl and drizzle with melted butter, 2 tablespoons lemon juice, and the sugar. Toss to coat and spread the fruit out in a single layer onto a parchment lined baking sheet. Bake until the pears are tender and the fruit is beginning to brown on the edges, about 25 to 30 minutes. Remove from the oven and set aside.
Meanwhile, place the honey, the remaining 1/4 cup lemon juice, canola oil, cream, lemon zest, 1 teaspoon salt, and 1/4 teaspoon pepper in a blender. Run the machine until the ingredients are well blended. Set aside.
To assemble the salad place the rocket, roasted fruit, and panettone croutons in a large bowl. Add the salad dressing and the remaining 1/2 teaspoon salt, and 1/4 teaspoon pepper. Toss to coat and serve immediately.