Heat oven to 425 degrees F and coat a mini muffin tin with cooking spray. Using a 2-inch round cutter, cut puff pastry into 48 rounds. Press rounds into the pan and prick bottoms with a fork; transfer to freezer while preparing filling.
Heat 1 tbsp of oil
in a skillet
over medium-high heat; add lamb and cook until browned, breaking up large chunks, about 3 min. Stir in tarragon, chives, cumin and garlic powder; transfer to a bowl
. Add remaining oil to the skillet and cook shallots and carrots over medium-high heat, 2 min. Add corn and cook 5 min. Return meat
mixture to pan and stir together. Mix in peas and season with salt and pepper to taste.
Scoop a small amount of the filling into each puff pastry cup
. Bake until pastry is golden brown, 18 to 20 min. Let cool slightly before removing pies from pans.
Transfer mashed potatoes to a piping bag filled with a star tip and pipe a dollop on each pie.