Melt butter in microwave or double boiler; stir in vanilla and cool completely. In large bowl, whisk together flour and sugar. Stir in butter mixture; add toffee bits and chopped pecans (mixture will be crumbly). Shape into 1 inch balls and place 2 inches apart on ungreased baking sheets (it is better to use parchment paper to bake them on as they might stick to the pan) Flatten slightly. Bake at 375 degrees for 12 minutes, or until edges begin to brown. DELISH!