Slightly soften ice cream. Puree half the peach pieces and the peach nectar in blender. Add ice cream. Pulse 6 to 8 times, until blended.
Pour into 8 x 8 x 2-inch metal pan. Place in freezer while preparing remaining ingredients.
Finely dice remaining peach pieces. Toast pecans in small skillet over medium-high heat, stirring, until lightly browned and fragrant, 3 minutes. Transfer to plate to cool.
Remove pan with ice cream mixture from freezer. Stir in chopped peaches, pecans, cookie pieces, nutmeg and cinnamon until well blended. Freeze until firm, about 6 hours or overnight. Serve in waffle bowls, if desired.