Heat oven to 350F. Grease bundt pan with butter or cooking spray. Place 1/3 of the pecans in the bottom of the bundt pan
Whisk together sugar, pumpkin pie spice and cinnamon in medium bowl. Quarter biscuits and roll pieces into sugar-spice mixture. Layer biscuit pieces in bundt pan, sprinkling remaining pecans between biscuits, until all biscuit pieces and pecans are used.
Place bundt pan on half-sheet tray, to prevent the mixture from overflowing.
Pumpkin Spice Sauce
In small saucepan, combine brown sugar, butter, spices and pumpkin. Stir until butter is completely melted and mixture is combined. Remove from heat and stir in vanilla.
Gently pour or spoon pumpkin spice sauce over the biscuit pieces, trying to coat/cover each one.
Bake for 35-40 minutes. Cool 10 minutes, then carefully turn over onto rimmed serving plate. Be careful when turning over, so as not to burn yourself with the hot butter sugar sauce. Serve immediately.