Preheat oven to 350°F (176ºC). Place pecans on a baking sheet and toast in preheated oven until fragrant, about 5 minutes. Let cool slightly.
In a food processor, coarsely grind the 3 1/2 cups vanilla wafer cookies until they form crumbs. Add pecans and blend until combined.
In a large bowl, combine cookie-pecan mixture with cocoa powder, confectioners' sugar, bourbon, corn syrup, vanilla extract, and salt. Stir until combined.
Using a tablespoon measure, scoop out the dough and roll it into 1-inch balls. Place on a parchment-lined baking sheet. Freeze for 10 minutes or until firm.
Melt together bittersweet chocolate and coconut oil in a double boiler over medium heat, stirring constantly until smooth.
Dip the balls into melted chocolate, using a fork to turn them, and coat evenly. Place on a parchment-lined baking sheet and top each ball with a single pecan half. Return to the freezer for 10 minutes to allow the chocolate coating to set before serving.