1. Beat cream cheese and sugars in a bowl with a mixer on medium speed until smooth. Then beat in pumpkin, half-and-half, salt, pumpkin pie spice, and vanilla until smooth and fluffy.
2. Lay enough graham crackers in a 9- by 9-in. pan to cover bottom (cut to fit if necessary). Spread a quarter of pumpkin mixture over crackers with an offset spatula. Layer 3 more times, ending with pumpkin mixture.
3. Cover; chill overnight. Set leaf cutouts (trace them on paper) on top and dust with cocoa, then remove. Cut cake into squares.
Note: Nutritional analysis is per square.
To serve it on a plate (out of the pan), line pan with plastic wrap so it hangs over the edges. Start your layers with a quarter of the pumpkin mixture, top with graham crackers, and repeat 3 times, ending with crackers. To serve, lift from pan using plastic wrap as handles. Hold a plate facedown on top of the cake and flip over together. Remove wrap, smooth with a spatula, and trim edges. Then decorate as directed.