Heat oven to 350 degrees. Coat a 2-qt deep baking dish with nonstick cooking spray. Set aside.
Place half of pound cake in a food processor. Pulse until no large pieces remain. Add second half of pound cake and pulse until crumbs are formed. Transfer to a large bowl. Stir in melted butter, almonds and 1 tsp pumpkin pie spice until blended.
In a second large bowl, combine apple slices, blueberries, brown sugar and remaining ½ tsp pumpkin pie spice. Toss to combine.
Sprinkle ½ c of crumb mixture into bottom of prepared dish, coating evenly. Top with half of the apple mixture and half of the remaining crumb mixture. Repeat, ending with remaining crumb mixture on top. Dot top of mixture with the cold butter pieces and cover dish with foil.
Bake at 350 degrees for 30 minutes, then uncover and continue to bake for another 30 minutes. Remove from oven; cool at least 15 minutes before serving with ice cream on the side, if desired.