Preheat oven to 350°F (175°C). Grease a 9-inch pie pan with nonstick spray.
In a clean, dry bowl, beat the egg whites with a mixer on medium speed until foamy. Gradually add sugar, 1 tablespoon at a time, beating until stiff peaks form.
Carefully fold in the crushed graham crackers, toasted pecans, and vanilla extract.
Spoon the meringue mixture into the prepared pie pan.
Bake for 25-30 minutes, until the meringue is set and lightly toasted.
Cool the pie at room temperature for at least 2 hours. Top with thawed whipped topping before serving.
Notes
For a gluten-free version, use gluten-free graham crackers. Store in the refrigerator for up to 3 days.