Spread chopped pecans and pecan halves in a single layer on a baking sheet. Toast in a preheated 350°F for 6-8 minutes. Set aside to cool.
Crush pecan shortbread cookies using a food processor until fine crumbs. Add to a mixing bowl with chopped pecans and powdered sugar. Mix together.
In a separate bowl or large measuring cup, whisk together Bourbon, butter, corn syrup and vanilla until fully combined. Pour into crumbs and mix until fully moistened.
Transfer to an airtight container and chill for 4 hours or overnight to set.
To make: Roll into 1-inch bite size balls. (Similar to a meatball.) Place onto a parchment lined pan and keep chilled, or pop into the freezer, while working in batches to coat.
To dip in chocolate: Melt chocolate with shortening in a double boiler over gently simmering water until smooth. Use two forks or a toothpick to dip the balls into chocolate to coat. Place onto a parchment lined tray. Immediately top one third with a single pecan half and sprinkle remaining with toffee bits. Chill until set.
To roll in powdered sugar: Pour 1 cup powdered sugar into a shallow dish. Roll one third of bourbon balls in powdered sugar until coated on all sides.
Store chilled in an airtight container for 3-5 days before serving.
May be kept chilled in an airtight container for up to 4 weeks.