How to Make It
Place yogurt in a large measuring cup with a spout; set aside. Combine cream, sugar, vanilla bean paste, and salt in a small saucepan. Heat over medium-low just until steaming, about 6 minutes. Meanwhile, stir together gelatin and 1 1/2 tablespoons cold water in a small bowl; let stand 5 minutes. Remove cream mixture from heat. Whisk gelatin mixture into cream mixture until incorporated. Pour mixture through a fine wire-mesh strainer into measuring cup with yogurt; discard any solids. Whisk yogurt mixture until smooth; divide evenly among 8 (4-ounce) lightly greased (with cooking spray) ramekins. Refrigerate, uncovered, at least 8 hours or up to 2 days.
Stir together sugar, 2/3 cup water, and salt in a small saucepan. Cook over medium-high, stirring often, until sugar is dissolved, about 4 minutes. Pour into a 13- x 9-inch metal baking pan. Stir in orange juice and orange blossom water. Freeze mixture, uncovered, until just set but not completely frozen, about 1 hour. Rake through granita using a fork, breaking up any large chunks. Return mixture to freezer; freeze until completely set and frozen, 2 to 3 hours. Rake through granita with a fork until it is completely broken up and no large chunks remain. Granita can be transferred to an airtight container and frozen up to 2 weeks.
Combine apricots and 2 tablespoons water in a small saucepan. Cover and cook over medium, stirring often, until apricots are softened, about 5 minutes. Stir in sugar. Cook, uncovered, stirring often and mashing apricots with back of spoon, until sugar melts and mixture has thickened and reduced to about 1 cup, 10 to 15 minutes. (To check if jam is thick enough, place 1 teaspoon jam on a chilled plate. Let stand 5 seconds, and drag a spoon through the center. If jam flows back into empty space, continue cooking.) Remove from heat, and stir in lemon juice and salt. Let cool to room temperature, about 1 hour. Jam can be chilled in an airtight container up to 1 week.
Preheat oven to 350°F. Place baguette slices in a single layer on a rimmed baking sheet. Drizzle with oil, and sprinkle with salt and pepper. Bake in preheated oven until crisp and golden brown, 6 to 8 minutes. Transfer crostini to a wire rack, and let cool completely, about 10 minutes. Break into small pieces.
To serve, place about 1 tablespoon apricot jam in each of 8 shallow serving bowls; spread jam into a 4-inch circle. Run a small offset spatula around edges of panna cotta. Dip bottom halfs of ramekins in hot water for 10 seconds. Invert panna cotta servings onto jam. Spoon about 1/4 cup granita around one side of each panna cotta. Sprinkle crostini pieces and chopped white chocolate over granita. Serve immediately. Reserve remaining granita and jam for another use.