How to Make It
Preheat oven to 375°.
Weigh or lightly spoon flour into a dry measuring cup. Combine flour, cornmeal, 1/4 cup sugar, 1/4 teaspoon salt, and rosemary in the bowl of a food processor; pulse 2 times to combine. With processor on, slowly add oil through food chute; process until crumbly. Press cornmeal mixture into bottom and up sides of a 9-inch round fluted removable-bottom tart pan coated with cooking spray. Chill 10 minutes. Line bottom of dough with a piece of foil coated with cooking spray; arrange pie weights or dried beans on foil. Bake at 375° for 20 minutes. Remove weights and foil; cool on a wire rack.
Combine 1/4 cup sugar, port, 3/4 cup water, and lemon rind strip in a medium saucepan, stirring with a whisk. Add pears; bring to a boil. Cover, reduce heat, and simmer 9 minutes or until pears are tender when pierced with a knife. Remove pears with a slotted spoon; cool slightly. Cut lengthwise into wedges. Increase heat to high. Bring port mixture to a boil; cook 6 minutes or until reduced to 1/4 cup. Discard lemon rind strip.
Combine remaining 2 tablespoons sugar, remaining 1/4 teaspoon salt, 1/4 cup milk, cornstarch, and yolk in a small saucepan, stirring with a whisk. Bring to a boil over medium heat, stirring frequently. Stir in remaining 1/2 cup milk; cook 1 minute, stirring constantly. Remove pan from heat; stir in ricotta, yogurt, 1 teaspoon grated rind, and vanilla. Cover and chill at least 1 hour.
Spread ricotta mixture evenly over bottom of crust. Arrange pear wedges over ricotta mixture. Drizzle with port mixture.