Preheat oven to 400°. Toss together first 3 ingredients. Spread in a single layer on a parchment paper-lined 15- x 10-inch jelly-roll pan. Bake 30 to 35 minutes or until lightly browned and tender. Reduce oven temperature to 350°. Let pears cool 20 minutes.
Meanwhile, bake pecans at 350° in a single layer in a shallow pan 6 to 8 minutes or until toasted and fragrant, stirring halfway through.
Stir together pears, mascarpone, and lemon zest. Beat cream and powdered sugar at high speed with an electric mixer until soft peaks form. Fold whipped cream mixture into pear mixture.
Spoon pear mixture into a zip-top plastic freezer bag; snip 1 corner of bag to make a 1-inch hole. Pipe pear mixture into cannoli shells. Place in a 13- x 9-inch pan. Cover and chill 2 hours before serving. Serve cannoli with warm Praline Sauce, and sprinkle with toasted pecans. Garnish, if desired.
Note: We tested with cannoli shells purchased from our grocer's bakery. Ask the bakery clerk if you don't see them.
Pair with: Saracco Moscato d'Asti.
Get Caramelized Pear Cannoli made, stuffed, and in the fridge 2 days ahead.