Preheat oven to 350°F. Spray interiors of jars with cooking spray. Add 2 tablespoons of pecans to each jar.
Mix corn syrup, eggs, sugar, butter and vanilla using a spoon. Pour a scant 1/4 cup filling into each jar. (Tip: Combine the corn syrup mixture in a 2-cup or larger glass measuring cup to pour easily into the jars). Place filled jars on a baking sheet or cake pan.
Bake on center rack of oven for 30 to 35 minutes. Pies are done when centers reach 200°F.
Cool for 2 hours on wire rack before serving.
Serve each with a dollop of whipped cream. Garnish with crumbled cookies if desired.
Note: If using another size jar (other than the 4-ounce size called for), be sure to leave about 3/4-inch between the pecan filling and the rim of the jar to avoid boilovers.