Preheat the oven to 350°F. Spread the pecan pieces on a baking sheet in a single layer. Toast for 6-8 minutes. Set aside 1/4 cup to garnish the top. Cool.
Make Spice Cake: Meanwhile, prepare the cake per the package directions using the amount of eggs, oil and water called for on the box. Bake according to directions in a 13x9-inch baking pan. Cool in the pan on a wire rack. After cooling completely, cut into 1-inch cubes.
Pumpkin Cheesecake Filling: In a large mixing bowl using an electric mixer, beat together the cream cheese, pumpkin, powdered sugar, pumpkin pie spice and vanilla. Whip for 2 minutes or until smooth, light and fluffy. Fold in one 8-oz whipped topping by hand.
To Assemble: Layer 1/3 cubed cake in the bottom of a large trifle bowl. Drizzle with 1/3 caramel sauce and sprinkle with 1/3 pecans. Top with 1/2 pumpkin cheesecake filling.
Arrange 1/3 cake over pumpkin filling, drizzle with 1/3 caramel sauce and sprinkle with 1/3 pecans. Spread with one 8-oz whipped topping.
Arrange final 1/3 cake over whipped topping, drizzle with final 1/3 caramel sauce and 1/3 pecans. Spread with remaining pumpkin cheesecake filling.
Frost the top as desired with remaining 8-oz whipped topping. Arrange Ginger Snaps on top and sprinkle with additional pecans or a dusting of cinnamon. Chill thoroughly for at least 4 hours or overnight.
Store leftovers chilled.
Homemade Whipped Cream: If you prefer to make your own whipped cream for this recipe, you can. You'll need the equivalent of 6 cups of whipped cream.Use 3 cups of heavy cream whipped with 1/3 cup granulated sugar and 1 teaspoon vanilla extract. Whip using a hand mixer until stiff peaks form then proceed with the trifle recipe. **Please note, fresh whipped cream isn't as stable as Cool Whip so add the topping on the day you plan on serving the pumpkin spice trifle.**