Preheat the oven to 350 degrees F. Lightly coat a 9-by-13-inch baking dish with cooking spray, then line with parchment paper, leaving an overhang on two sides. Lightly coat the parchment with cooking spray. Spread the pecans on a baking sheet and bake until toasted, 8 to 10 minutes; let cool.
Finely grind the nuts in a food processor. Add the flour, 1/2 cup sugar and 1 teaspoon salt and pulse. Add 1 1/2 sticks butter and 2 egg yolks; process until the dough comes together. Transfer the dough to the prepared baking dish and press into an even layer (use a piece of parchment to help). Bake until the crust is golden brown, 30 to 35 minutes. Let cool.
Sprinkle the gelatin over 2 tablespoons warm water in a small microwave-safe bowl and stir to combine. Microwave in 10-second intervals, stirring after each, until melted.
Combine the cranberries, vanilla bean and 3/4 cup sugar in a medium saucepan. Stir in 2 tablespoons warm water and cook over medium-high heat, stirring, until thick, 10 to 15 minutes. Discard the vanilla bean. Transfer the mixture to a blender, add the gelatin mixture and puree on low speed until smooth but not too airy; set aside.
Meanwhile, whisk the 3 whole eggs, remaining 2 egg yolks, the lemon zest, lemon juice and the remaining 1/2 cup sugar and 1/4 teaspoon salt in a medium saucepan. Cook over medium heat, whisking, until thick enough to coat the back of a spoon, 5 to 10 minutes (do not boil). Remove from the heat and whisk in the remaining 1 1/2 sticks butter, one piece at a time, until creamy. Whisk in the cranberry mixture until combined. Spread the cranberry mixture over the cooled crust and refrigerate, uncovered, at least 6 hours and up to 1 day.
Lift the bars out of the pan and remove the parchment. Cut into small squares.