Place pecan pieces in bottom of muffin tins. Make caramel as follows: Melt butter in large skillet. Add brown sugar and vanilla. Stir constantly until sugar is melted and smooth. Pour caramel over pecan pieces. Top with uncooked biscuits. Bake in oven until biscuits are golden brown per directions on can. Do not cool!!! Spoon out each biscuit and caramel topping (like an upside down cake) and serve warm.