Preheat the oven to 375°F (190°C) and lightly grease a 9x13-inch baking dish.
In a bowl, stir together 1 cup (125 g) flour, ½ cup (60 g) chopped pecans, and 2 tablespoons (25 g) granulated sugar. Pour in ½ cup (113 g) melted butter and mix until the crumbs are evenly damp and hold together when pressed.
Tip the mixture into the dish and press it into a firm, even layer across the bottom. Bake for 12 minutes, or until the edges turn light golden. Set the dish on a rack and cool completely before adding anything on top.
Beat 8 oz (226 g) softened cream cheese on medium until smooth, about one minute. Add 1 cup (120 g) powdered sugar and ½ teaspoon vanilla, then beat until no lumps remain.
Fold in 1 cup of the thawed whipped topping by hand with a silicone spatula until just combined. Spread this over the cooled crust in an even layer, working gently so you don't pull up crumbs.
In a separate bowl, whisk 2 packages of instant cheesecake pudding mix with 3 cups (720 ml) cold milk for about 2 minutes, until the mixture visibly thickens and starts to hold soft ridges. Fold in another 1 cup of the whipped topping until smooth.
Spread the pudding gently over the cream cheese layer. Chill the pan for 20 minutes at this stage so the pudding firms up before the fruit goes on.
Spoon the full 21 oz (595 g) can of cherry pie filling over the set pudding. Spread it out carefully with the back of a spoon, keeping it to a single even layer and working from the center outward.
Spread the remaining whipped topping (about 2 cups) over the cherries in soft swoops. Scatter 2 tablespoons (15 g) chopped pecans over the top for a little crunch.
Cover the dish and refrigerate for at least 4 hours, or overnight, until every layer is set firm. Slice into 15 squares with a knife wiped clean between cuts for tidy edges.